A high-speed surface-mounted permanent magnet motor rotor structure and manufacturing method

Abstract

A high-speed surface-mounted permanent magnet motor rotor structure and manufacturing method, comprising a rotor core, permanent magnets and a protective cover arranged in sequence from the inside to the outside in the radial direction, the permanent magnets are symmetrically arranged in pairs, and a filler for reducing the deformation stress of the permanent magnets is arranged in the circumferential gap between adjacent permanent magnets; the protective cover comprises an inner carbon fiber layer, a mixed layer, a copper shielding layer and an outer carbon fiber layer arranged in sequence from the inside to the outside in the radial direction; the mixed layer is wound by a carbon fiber pre-wound tape, and the carbon fiber pre-wound tape includes a variable density structure, and the variable density structure is formed by adjusting the amount of magnetic powder and colloid material sprayed on the carbon fiber tape during the winding process. Provided is a high-speed surface-mounted permanent magnet motor rotor structure that can adjust the air gap magnetic field after the rotor is magnetized as a whole by adjusting the content of the sprayed magnetic powder.

Description

Technical Field

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

[0002] High-speed permanent magnet motors have the characteristics of high speed and high power density. They can effectively save motor materials and realize high-speed direct-drive loads. They have broad application prospects in high-speed grinders, high-speed centrifugal compressors, high-speed blowers, high-speed aircraft generators and other fields.

[0003] The high-speed surface-mounted permanent magnet motor rotor is the most widely used high-speed permanent magnet motor rotor structure. Its rotor is subjected to very large centrifugal force when rotating at high speed, and the permanent magnet is very easy to be damaged after the tensile stress is applied. Generally, its tensile strength does not exceed 80MPa. Therefore, the outer side of the permanent magnet of the high-speed permanent magnet motor rotor needs to be protected by a protective cover. At present, there are two main protection methods. One protection method is to use a high-strength non-magnetic metal sheath on the outside of the permanent magnet. However, due to the effect of stator space harmonics and time harmonics, a large amount of eddy current loss is generated on the protective cover, thereby aggravating the increase of rotor temperature rise, resulting in partial demagnetization or demagnetization of the permanent magnet; another protection method is to use carbon fiber binding tape to protect the rotor permanent magnet. However, carbon fiber is a poor conductor of heat, which is not conducive to the heat dissipation of the permanent magnet rotor, and it is also easy to cause overheating and demagnetization of the permanent magnet.

[0004] In summary, the maximum power and maximum speed of the existing surface-mounted rotor high-speed permanent magnet motor are limited by the rotor structure and it is difficult to further improve them. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a high-speed surface-mounted permanent magnet motor rotor structure and a manufacturing method, which adjusts the air gap magnetic field after the rotor is magnetized as a whole by adjusting the content of the sprayed magnetic powder.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A high-speed surface-mounted permanent magnet motor rotor structure, comprising a rotor core, permanent magnets and a protective cover arranged in sequence from the inside to the outside in a radial direction, wherein the permanent magnets are symmetrically arranged in pairs and sleeved on the outer surface of the rotor core, and a filler body for reducing the deformation stress of the permanent magnet is arranged in the circumferential gap between adjacent permanent magnets, and the filler body and the permanent magnet together form a torus; the protective cover comprises an inner carbon fiber layer, a mixed layer, a copper shielding layer and an outer carbon fiber layer arranged in sequence from the inside to the outside in a radial direction, an inner carbon fiber layer is arranged on the outer surface of the torus body, a mixed layer is arranged on the outer surface of the inner carbon fiber layer, a copper shielding layer is arranged on the outer surface of the mixed layer, and an outer carbon fiber layer is arranged on the outer surface of the copper shielding layer; the mixed layer is wound by a carbon fiber pre-wound tape, and the carbon fiber pre-wound tape includes a variable density structure;

[0008] The carbon fiber pre-wound tape comprises a carbon fiber tape, wherein the carbon fiber pre-wound tape with an equal density structure is formed by spraying and bonding magnetic powder and colloid material on the surface of the carbon fiber tape in an equal volume ratio, and the carbon fiber pre-wound tape has an equal density structure; the carbon fiber pre-wound tape with a variable density structure is formed by spraying and bonding magnetic powder and colloid material on the surface of the carbon fiber tape in a variable volume ratio, and the carbon fiber pre-wound tape has a variable density structure;

[0009] In the carbon fiber pre-wound tape with a variable density structure, the spraying amount of the magnetic powder is distributed in a sinusoidal pattern along the circumferential direction;

[0010] The magnetic powder spraying amount at the position along the symmetrical center line of the permanent magnet is the highest, and the magnetic powder spraying amount at the circumferential positions on both sides gradually decreases according to the sine law.

[0011] The mixed layer is formed by winding a carbon fiber prewound tape with a variable density structure, winding a carbon fiber prewound tape with an equal density structure into an equal density layer, and then winding a carbon fiber prewound tape with a variable density structure on the outside of the equal density layer to form a variable density layer combination, or winding a carbon fiber prewound tape with a variable thickness structure into a variable thickness layer, and then winding a carbon fiber prewound tape with a variable density structure on the outside of the variable thickness layer to form a variable density layer combination.

[0012] The variable density structure is formed by adjusting the spraying amount of magnetic powder and the spraying amount of colloid material respectively during the winding process of the carbon fiber pre-wound tape, and the increase or decrease of the magnetic powder is equal to the decrease or increase of the colloid material.

[0013] The filler is a mixture of bonding permanent magnet powder and colloidal resin; the volume density of the filler is cosine distributed along the circumferential direction of the annular body.

[0014] The inner carbon fiber layer applies a compressive stress of ≥200 MPa radially inward to the outer surfaces of the permanent magnet and the filler.

[0015] The inner carbon fiber layer is a multi-layer structure, with the number of layers being ≤4 and the thickness of a single layer being ≤0.15mm; the thickness of a single layer of the outer carbon fiber layer being ≤2mm and the surface roughness being ≤0.1mm.

[0016] The above-mentioned method for manufacturing a high-speed surface-mounted permanent magnet motor rotor structure comprises the following steps:

[0017] Step 1: spraying and bonding magnetic powder and colloid material on the surface of carbon fiber tape in equal volume ratio or variable volume ratio to form a carbon fiber pre-wound tape with equal density structure or a carbon fiber pre-wound tape with variable density structure; after uniformly mixing magnetic powder and colloid material in a volume ratio of 2:1, spraying and curing, flattening and bonding them on the surface of carbon fiber tape to form a carbon fiber pre-wound tape with variable thickness;

[0018] Step 2, directly bonding the paired permanent magnets to the outer circumferential surface of the rotor core, and filling the gaps formed between the permanent magnets with a filler; winding the inner carbon fiber layer on the outside of the annular body formed by the permanent magnet and the filler by applying tensile stress; winding a carbon fiber pre-wound tape with a variable density structure on the outside of the inner carbon fiber layer by applying tensile stress to form a mixed layer; or first winding a carbon fiber pre-wound tape with an equal density structure by applying tensile stress, and then winding a carbon fiber pre-wound tape with a variable density structure to form a mixed layer; or first winding a carbon fiber pre-wound tape with a variable thickness by applying tensile stress, and then winding a carbon fiber pre-wound tape with a variable density structure to form a mixed layer; sleeve the copper shielding layer on the outside of the mixed layer; wind the outer carbon fiber layer on the outside of the copper shielding layer by applying tensile stress, and the rotor structure of the high-speed surface-mounted permanent magnet motor is completed.

[0019] The beneficial effects of the present invention are:

[0020] 1. In the winding process of the present invention, if the magnetic powder and the colloid material are sprayed and bonded on the surface of the carbon fiber tape according to an equal volume ratio, the formed carbon fiber pre-wound tape is an equal density structure; if the magnetic powder and the colloid material are sprayed and bonded on the surface of the carbon fiber tape according to a variable volume ratio, that is, in the winding process, the amount of magnetic powder sprayed is adjusted, and the formed carbon fiber pre-wound tape is a variable density structure. After the rotor is magnetized as a whole, the gas magnetic field generated in the place with high magnetic powder content is strong, and the gas magnetic field generated in the place with low content is weak. The present invention effectively reduces the rotor eddy current loss and air friction loss, alleviates the risk of permanent magnet damage caused by excessive local stress inside the rotor, breaks through the technical difficulties of high-speed permanent magnet motors to develop higher speeds and greater power, and also effectively improves the reliability of rotor operation.

[0021] 2. The density of magnetic powder in the circumferential direction changes in a sinusoidal (or cosine) pattern, so that the air gap magnetic field generated after magnetization can also be sinusoidal or cosine. The magnetic powder content density in the circumferential direction can be changed according to the needs of the air gap magnetic field waveform to achieve regulation of the air gap magnetic field. It can also be regulated to form other non-sinusoidal magnetic field waveforms to meet the needs of the motor, and has a wide range of uses. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the axial structure of the rotor structure of a high-speed surface-mounted permanent magnet motor;

[0023] Figure 2 It is a schematic diagram of the winding hybrid layer of the high-speed surface-mounted permanent magnet motor rotor structure;

[0024] Figure 3 It is a schematic diagram of the magnetic powder density distribution of the carbon fiber pre-wound tape;

[0025] Figure 4 It is a schematic diagram of the rotor structure of a high-speed surface-mounted permanent magnet motor with a variable density layer and equal density layer;

[0026] Figure 5 It is a schematic diagram of the rotor structure of a high-speed surface-mounted permanent magnet motor with a variable density layer and variable thickness layer;

[0027] Figure 6 It is a schematic diagram of the structure of a variable density layer and a variable thickness layer;

[0028] 1. rotor core, 2. permanent magnet, 3. filling body, 4. inner carbon fiber layer, 5. mixed layer, 6. copper shielding layer, 7. outer carbon fiber layer, 51. carbon fiber tape, 52. variable density layer, 53. equal density layer, 54. variable thickness layer. DETAILED DESCRIPTION

[0029] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings and preferred embodiments of the present invention, but the protection scope of the present invention is not limited to the following specific embodiments.

[0030] Example 1

[0031] like Figures 1 to 3As shown, a high-speed surface-mounted permanent magnet motor rotor structure includes a rotor core 1, permanent magnets 2 and a protective cover arranged in sequence from the inside to the outside in a radial direction. Two pairs of permanent magnets 2 are symmetrically bonded to the outer surface of the rotor core 1. The permanent magnets 2 generally have a large residual magnetism and produce a large air gap flux density. Since the average radius of the position where they are located is small, the stress caused by the centrifugal force is very small, which can effectively reduce the risk of the permanent magnets 2 being damaged by force. A mixture of bonding permanent magnet powder and colloidal resin is arranged in the circumferential gap between adjacent permanent magnets 2 as a filling body 3. The permanent magnets 2 are prone to deformation after being affected by temperature. Due to the hardness of the mixture of bonding permanent magnet powder and colloidal resin The filling body 3 has a relatively low density and good toughness, and can effectively absorb the deformation stress of the permanent magnet 2. At the same time, the volume density of the filling body 3 is cosine-distributed along the circumferential direction, that is, the volume density is filled with variable density along the circumferential direction according to the cosine value of the ratio of the circumferential angle to the pole pitch at the position, and the volume density of the bonding permanent magnet powder is increased in the filling body 3 part close to the permanent magnet 2, and is combined with the permanent magnet 2 to form a variable magnetic field in the circumferential direction, and its magnetic field distribution is cosine-varying. The high-speed surface-mounted permanent magnet motor with this structure is magnetized as a whole, and a magnetic field with a sinusoidal distribution along the circumferential direction will be formed on its outside. The protective cover includes an inner carbon fiber layer arranged in sequence from the inside to the outside along the radial direction. 4, a mixed layer 5, a copper shielding layer 6 and an outer carbon fiber layer 7, the inner carbon fiber layer 4 is a multi-layer structure, the number of layers is 4, the thickness of a single layer is 0.15mm, the inner carbon fiber layer 4 is wound on the outside of the permanent magnet 2 by applying tensile stress, and a large pre-pressure is applied during the winding process to ensure that after the winding is completed, a compressive stress of 350MPa is applied radially inward to the outer surface of the permanent magnet 2 and the filling body 3, so that not only the permanent magnet 2 and the filling body 3 wrapped therein can be integrated, but also the permanent magnet 2 is not subjected to tensile stress when the rotor rotates at high speed, so as to avoid damage to the permanent magnet 2 due to excessive tensile stress, and the mixed layer 5 is wound on the outside of the permanent magnet 2 by applying tensile stress. The outer carbon fiber layer 4 is wound by applying tensile stress, and the copper shielding layer 6 is sleeved on the outer side of the mixed layer 5 by interference fit. The copper shielding layer 6 can effectively shield the high-frequency time-varying magnetic field harmonics introduced when the stator winding is powered by the inverter and the high-frequency space magnetic field harmonics caused by the motor structure, so it can effectively reduce the eddy current loss caused by the high-frequency magnetic field inside the rotor, and can also reduce the rotor temperature rise, so as to further improve the maximum power of the motor. The outer carbon fiber layer 7 is wound on the outer side of the copper shielding layer 6 by applying tensile stress. The single layer thickness of the outer carbon fiber layer 7 is 2mm, the surface roughness is 0.1mm, and the outer surface roughness is less than 0.The 1mm smooth rotor surface can effectively reduce the air friction loss generated during high-speed rotation, thereby effectively reducing the loss and temperature rise on the rotor, and further improving the efficiency of the motor. The mixed layer 5 is wound by a carbon fiber pre-wound tape with a variable density structure. During the winding process, the magnetic powder and the colloid material are sprayed and bonded to the surface of the carbon fiber tape 51 according to a variable volume ratio, that is, during the winding process, the spraying amount of the magnetic powder is adjusted. The formed carbon fiber pre-wound tape has a variable density structure. After the rotor is magnetized as a whole, the air magnetic field generated at the place with high magnetic powder content is strong, and the air magnetic field generated at the place with low content is weak. Due to the variable density structure, the spraying amount of magnetic powder is sinusoidally distributed along the circumferential direction. Even if the magnetic powder content is highest near the axis of the permanent magnet 2 and gradually decreases according to the sinusoidal law away from the axis, a high-sinusoidal air gap magnetic field will be generated after the rotor is magnetized as a whole, reducing the spatial harmonic content of the magnetic field inside the motor, thereby effectively reducing the high-frequency eddy current loss and internal temperature rise inside the motor. In addition, the carbon fiber pre-wound tape is formed by spraying and bonding magnetic powder and colloid material on the surface of the carbon fiber tape 51, so each additional layer of carbon fiber pre-wound tape will increase a layer of carbon fiber tape 51, thereby increasing the strength of the rotor and helping to increase the upper limit of the maximum speed of the motor.

[0032] A method for manufacturing a high-speed surface-mounted permanent magnet motor rotor structure comprises the following steps:

[0033] Step 1, spraying and bonding magnetic powder and colloid material on the surface of the carbon fiber tape 51 in equal volume ratio to form a carbon fiber pre-wound tape with equal density structure;

[0034] Step 2, directly bond the paired permanent magnets 2 to the outer circumferential surface of the rotor core 1, and fill the filler 3 in the gap formed between the permanent magnets 2; wind the inner carbon fiber layer 4 on the outside of the annular body formed by the permanent magnet 2 and the filler 3 by applying tensile stress; wind the carbon fiber pre-wound tape with a variable density structure on the outside of the inner carbon fiber layer 4 by applying tensile stress to form a mixed layer 5; sleeve the copper shielding layer 6 on the outside of the mixed layer 5; wind the outer carbon fiber layer 7 on the outside of the copper shielding layer 6 by applying tensile stress, and the high-speed surface-mounted permanent magnet motor rotor structure is completed.

[0035] Example 2

[0036] The difference between Example 2 and Example 1 is that Figure 4 As shown, the mixed layer 5 is an equal density layer 53 formed by winding an equal density carbon fiber pre-wound tape, and then a variable density layer 52 is formed by winding a variable density carbon fiber pre-wound tape on the outside of the equal density layer 53. The variable density layer 52 and the equal density layer 53 together constitute the mixed layer 5.

[0037] Example 3

[0038] The difference between Example 3 and Example 1 is that Figure 5 and Figure 6 As shown, the mixed layer 5 is a variable thickness layer 54 formed by winding a variable thickness carbon fiber prewound tape, and then a variable density carbon fiber prewound tape is wound on the outside of the variable thickness layer 54 to form a variable density layer 52, and the variable density layer 52 and the variable thickness layer 54 together form the mixed layer 5. During the winding process of the carbon fiber prewound tape, the amount of magnetic powder and colloid material sprayed on the surface of the carbon fiber tape 51 is gradually reduced from the inside to the outside in the radial direction, so that a structure with a thick inner layer and a thin outer layer can be formed.

[0039] Since the radius of the variable density layer 52 is small, the local stress generated by the centrifugal force on the same volume of carbon fiber pre-wound tape is small. Therefore, when making the carbon fiber pre-wound tape bonded to the inner layer, the spraying amount of magnetic powder and colloid material is reduced in real time during the winding process, thereby reducing the thickness of the carbon fiber pre-wound tape, so that the volume of magnetic powder close to the air gap is larger, and the air gap magnetic density generated after magnetization can be larger, thereby effectively utilizing the magnetic material.

[0040] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. For those skilled in the art, improvements and changes obtained without departing from the technical concept of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A high-speed surface-mounted permanent magnet motor rotor structure, characterized in that: It comprises a rotor core, permanent magnets and a protective cover which are arranged in sequence from the inside to the outside in the radial direction, wherein the permanent magnets are symmetrically arranged in pairs and are sleeved on the outer surface of the rotor core, and a filling body for reducing the deformation stress of the permanent magnets is arranged in the circumferential gaps between the adjacent permanent magnets, and the filling body and the permanent magnets together form a torus; the protective cover comprises an inner carbon fiber layer, a mixed layer, a copper shielding layer and an outer carbon fiber layer which are arranged in sequence from the inside to the outside in the radial direction, an inner carbon fiber layer is arranged on the outer surface of the torus body, a mixed layer is arranged on the outer surface of the inner carbon fiber layer, a copper shielding layer is arranged on the outer surface of the mixed layer, and an outer carbon fiber layer is arranged on the outer surface of the copper shielding layer; the mixed layer is wound by a carbon fiber pre-wound tape, and the carbon fiber pre-wound tape comprises a variable density structure; The carbon fiber pre-wound tape comprises a carbon fiber tape, wherein the carbon fiber pre-wound tape with an equal density structure is formed by spraying and bonding magnetic powder and colloid material on the surface of the carbon fiber tape in an equal volume ratio, and the carbon fiber pre-wound tape has an equal density structure; the carbon fiber pre-wound tape with a variable density structure is formed by spraying and bonding magnetic powder and colloid material on the surface of the carbon fiber tape in a variable volume ratio, and the carbon fiber pre-wound tape has a variable density structure; In the carbon fiber pre-wound tape with a variable density structure, the spraying amount of the magnetic powder is distributed in a sinusoidal pattern along the circumferential direction; The magnetic powder spraying amount at the position along the symmetrical center line of the permanent magnet is the highest, and the magnetic powder spraying amount at the circumferential positions on both sides gradually decreases according to the sine law.

2. A high-speed surface-mounted permanent magnet motor rotor structure according to claim 1, characterized in that: The mixed layer is formed by winding a carbon fiber prewound tape with a variable density structure, winding a carbon fiber prewound tape with an equal density structure into an equal density layer, and then winding a carbon fiber prewound tape with a variable density structure on the outside of the equal density layer to form a variable density layer combination, or winding a carbon fiber prewound tape with a variable thickness structure into a variable thickness layer, and then winding a carbon fiber prewound tape with a variable density structure on the outside of the variable thickness layer to form a variable density layer combination.

3. The high-speed surface-mounted permanent magnet motor rotor structure according to claim 1, characterized in that: The variable density structure is formed by adjusting the spraying amount of magnetic powder and the spraying amount of colloid material respectively during the winding process of the carbon fiber pre-wound tape, and the increase or decrease of the magnetic powder is equal to the decrease or increase of the colloid material.

4. The high-speed surface-mounted permanent magnet motor rotor structure according to claim 1, characterized in that: The filler is a mixture of bonding permanent magnet powder and colloidal resin; the volume density of the filler is cosine distributed along the circumferential direction of the annular body.

5. The high-speed surface-mounted permanent magnet motor rotor structure according to claim 1, characterized in that: The inner carbon fiber layer applies a compressive stress of ≥200 MPa radially inward to the outer surfaces of the permanent magnet and the filler.

6. The high-speed surface-mounted permanent magnet motor rotor structure according to claim 1, characterized in that: The inner carbon fiber layer is a multi-layer structure, with the number of layers being ≤4 and the thickness of a single layer being ≤0.15mm; the thickness of a single layer of the outer carbon fiber layer being ≤2mm and the surface roughness being ≤0.1mm.

7. The method for manufacturing a high-speed surface-mounted permanent magnet motor rotor structure according to claim 1, characterized in that: The following steps are involved: Step 1: spraying and bonding magnetic powder and colloid material on the surface of carbon fiber tape in equal volume ratio or variable volume ratio to form a carbon fiber pre-wound tape with equal density structure or a carbon fiber pre-wound tape with variable density structure; after uniformly mixing magnetic powder and colloid material in a volume ratio of 2:1, spraying and curing, flattening and bonding them on the surface of carbon fiber tape to form a carbon fiber pre-wound tape with variable thickness; Step 2, directly bonding the paired permanent magnets to the outer circumferential surface of the rotor core, and filling the gaps formed between the permanent magnets with a filler; winding the inner carbon fiber layer on the outside of the annular body formed by the permanent magnet and the filler by applying tensile stress; winding a carbon fiber pre-wound tape with a variable density structure on the outside of the inner carbon fiber layer by applying tensile stress to form a mixed layer; or first winding a carbon fiber pre-wound tape with an equal density structure by applying tensile stress, and then winding a carbon fiber pre-wound tape with a variable density structure to form a mixed layer; or first winding a carbon fiber pre-wound tape with a variable thickness by applying tensile stress, and then winding a carbon fiber pre-wound tape with a variable density structure to form a mixed layer; sleeve the copper shielding layer on the outside of the mixed layer; wind the outer carbon fiber layer on the outside of the copper shielding layer by applying tensile stress, and the rotor structure of the high-speed surface-mounted permanent magnet motor is completed.

Images