A hybrid excitation high-speed permanent magnet motor rotor and manufacturing method

Abstract

A hybrid excitation high-speed permanent magnet motor rotor and a manufacturing method thereof, comprising a rotating shaft, a sintered permanent magnet unit, a magnetic powder film and carbon fiber composite unit and a rotor sleeve arranged in sequence from the inside to the outside in the radial direction; the sintered permanent magnet unit is composed of a sintered permanent magnet block, an epoxy resin filler and a carbon fiber layer, the sintered permanent magnet block is equal in axial length and unequal in radial thickness, and the sintered permanent magnet block is arranged in a circumferential direction in a high-middle-low arrangement to form each magnetic pole of the high-speed permanent magnet motor rotor; the magnetic powder film and carbon fiber composite unit is composed of a plurality of magnetic powder film and carbon fiber composite sub-units composed of a magnetic powder film layer and a carbon fiber layer, the number of magnetic powder film layers and carbon fiber layers is unequal, but the sum of the number of layers remains unchanged. The present invention can improve the mechanical strength of the motor rotor, reduce the eddy current loss of the motor rotor, and increase the allowable linear speed of the motor rotor, thereby solving the problem of large temperature rise and low allowable linear speed of the eddy current loss of the traditional high-speed permanent magnet motor rotor.

Description

Technical Field

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

[0002] High-speed motor systems have significant advantages such as high power density and reliability, small size, light weight, and easy high-speed direct drive (eliminating the gearbox). They are very suitable for and can meet the special requirements of high-end equipment and green manufacturing. They have broad application prospects in high-speed grinders, air circulation refrigeration systems, energy storage flywheels, high-speed centrifugal compressors for natural gas transportation, and distributed power generation systems as aircraft or shipboard power supply equipment.

[0003] At present, there are three main types of high-speed motors: induction motors, switched reluctance motors, and permanent magnet motors. Permanent magnet motors are particularly suitable for high-speed and high-performance motor systems due to their outstanding advantages such as high efficiency and power factor and wide speed range. They have now become the mainstream of high-speed motor research and application. However, the existing high-speed permanent magnet motors have large rotor losses and high temperature rises, mechanical strength is difficult to reliably guarantee, and the allowable linear speed is low, which limits their development towards higher power and higher speed. In addition, due to the limitations of rotor strength and temperature rise, it is difficult to further improve the difficulty coefficient and operating quality (high power, high speed, high efficiency and high power factor, etc.) of existing high-speed permanent magnet motors. It is necessary to explore new rotor topologies for high-speed permanent magnet motors. Summary of the invention

[0004] The present invention proposes a hybrid excitation high-speed permanent magnet motor rotor and a manufacturing method, the purpose of which is to reduce the eddy current loss in the motor rotor, improve the mechanical strength and allowable linear speed of the motor rotor while ensuring the strength of the excitation magnetic field of the traditional high-speed permanent magnet motor rotor, break through the bottleneck technology that restricts the development of high-speed permanent magnet motors to higher power and higher speed, that is, the bottleneck technology that the power and speed improvement are limited by the temperature rise and strength of the rotor, and improve the operating quality of existing high-speed permanent magnet motors.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A hybrid excitation high-speed permanent magnet motor rotor, comprising a rotating shaft, a sintered permanent magnet unit, a magnetic powder film and carbon fiber composite unit and a rotor sleeve; the rotating shaft is located at the innermost side of the high-speed permanent magnet motor rotor, the sintered permanent magnet unit is coaxially sleeved on the outer side of the rotating shaft, the magnetic powder film and carbon fiber composite unit is coaxially sleeved on the outer side of the sintered permanent magnet unit, the rotor sleeve is arranged on the outer side of the magnetic powder film and carbon fiber composite unit, and the rotor sleeve is located at the outermost side of the high-speed permanent magnet motor rotor and is composed of multiple carbon fiber layers III;

[0007] The sintered permanent magnet unit includes a sintered permanent magnet block, a filling body and a carbon fiber layer I. The gap formed between adjacent sintered permanent magnet blocks is filled with the filling body. The filling body and the sintered permanent magnet block together form an annular body, and the carbon fiber layer I is wound on the outside of the annular body. The magnetic poles of each high-speed permanent magnet motor rotor are composed of a plurality of sintered permanent magnet blocks. The pole arc coefficients of the plurality of sintered permanent magnet blocks are the same, and the sintered permanent magnet blocks are arranged in a circumferential direction in a middle-high and two-end low arrangement. The sintered permanent magnet blocks have the same axial length and different radial thicknesses.

[0008] The number of carbon fiber layers III constituting the rotor sleeve is ≤10.

[0009] The number of magnetic poles of the high-speed permanent magnet motor rotor is an even number; the filler is composed of epoxy resin filler, the number of layers of the carbon fiber layer I is ≤4 layers, and the winding thickness is ≤0.8mm.

[0010] The magnetic powder film and carbon fiber composite unit is composed of a plurality of magnetic powder film and carbon fiber composite sub-units, the inner layer of the magnetic powder film and carbon fiber composite sub-unit is composed of a plurality of magnetic powder film layers, the outer layer is composed of a plurality of carbon fiber layers II, and the outer layer is arranged on the outer side of the inner layer; the number of layers of the magnetic powder film layer and the number of layers of the carbon fiber layer II in the magnetic powder film and carbon fiber composite sub-unit are not fixed, and the sum of the number of layers of the magnetic powder film layer and the carbon fiber layer II in the magnetic powder film and carbon fiber composite sub-unit is fixed; the number of layers of the magnetic powder film layer is the smallest in the radius of the magnetic powder film layer. The maximum value is reached in the magnetic powder film and carbon fiber composite subunit, and the number of layers decreases with the increase of the radius of the magnetic powder film and carbon fiber composite subunit. The number of layers of the carbon fiber layer II reaches the minimum value in the magnetic powder film and carbon fiber composite subunit with the smallest radius, and the number of layers increases with the increase of the radius of the magnetic powder film and carbon fiber composite subunit. The magnetic powder film layer is formed by uniformly mixing magnetic powder and epoxy resin in a certain proportion and then curing. The content of neodymium iron boron magnetic powder in the magnetic powder film layer is ≥60%, and the single layer thickness of the magnetic powder film layer is 0.2mm-0.25mm.

[0011] The sintered permanent magnet block adopts neodymium iron boron (NdFeB) permanent magnet with high remanence density; the carbon fiber layer I, carbon fiber layer II and carbon fiber layer III all adopt carbon fiber with good tensile performance; the rotating shaft is a magnetic shaft, which is made of material with good magnetic conductivity.

[0012] The composite rotor will be magnetized as a whole by a pulsed strong magnetic field generating device consisting of a capacitor bank, a thyristor, a charge and discharge control circuit and a magnetizing head (or a magnetizing coil), thereby forming a number of even poles.

[0013] A method for manufacturing a hybrid excitation high-speed permanent magnet motor rotor comprises the following steps:

[0014] Step 1, uniformly mix magnetic powder and epoxy resin in a certain proportion and solidify them to form a magnetic powder film layer block; and wind a carbon fiber layer II on the outside of the magnetic powder film layer block to form a magnetic powder film and carbon fiber composite subunit;

[0015] Step 2, sticking the sintered permanent magnet block to the outer cylindrical surface of the rotating shaft; filling the epoxy resin filler in the gap between the adjacent sintered permanent magnet blocks, the epoxy resin filler and the sintered permanent magnet block together form an annular body, and winding the carbon fiber layer I on the outside of the annular body by applying tensile stress; the magnetic powder film and carbon fiber composite sub-unit prepared in step 1 are successively wrapped around the outside of the carbon fiber layer I through interference fit, and the carbon fiber layer III is wound on the outside of the magnetic powder film and the carbon fiber composite unit by applying tensile stress, and the installation is completed.

[0016] The beneficial effects of the present invention are:

[0017] The high-speed permanent magnet motor rotor of the present invention includes a rotating shaft, a sintered permanent magnet unit, a magnetic powder film and a carbon fiber composite unit and a rotor sleeve. The sintered permanent magnet unit in the present application can not only ensure that the motor rotor generates an excitation magnetic field intensity comparable to that of a conventional high-speed permanent magnet motor rotor, but also ensure that it generates an air gap magnetic field with a high sinusoidal degree, thereby reducing the high-order harmonic content in the motor and reducing the eddy current loss in the high-speed permanent magnet motor rotor; the magnetic material in the magnetic powder film and the carbon fiber composite unit of the high-speed permanent magnet motor rotor is in a magnetic powder state, and the discontinuity of the magnetic powder and the non-conductivity of the film almost eliminate the rotor eddy current, and greatly reduce the effect of high-frequency electromagnetic waves on the sintered permanent magnet, thereby achieving near-zero rotor eddy current loss, which can greatly reduce the rotor temperature rise. In addition, the sintered permanent magnet unit, the magnetic powder film and the carbon fiber composite unit and the rotor sleeve of the high-speed permanent magnet motor rotor all contain carbon fiber materials, which can make the maximum allowable linear speed of the motor rotor reach 1300m / s, thereby greatly improving the power density of the motor. In summary, the high-speed permanent magnet motor rotor improves the operating quality of existing high-speed permanent magnet motors, namely high power, high speed, high efficiency and high power factor, and explores a new path for the development of high-speed permanent magnet motors towards higher power and higher speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the rotor structure of the hybrid excitation high-speed permanent magnet motor of the present invention;

[0019] Figure 2 It is a schematic diagram of the structure of the sintered permanent magnet unit of the hybrid excitation high-speed permanent magnet motor rotor of the present invention;

[0020] Figure 3 It is a schematic diagram of the structure of the magnetic powder film and carbon fiber composite unit of the hybrid excitation high-speed permanent magnet motor rotor of the present invention;

[0021] Figure 4 It is a schematic diagram of the structure of the magnetic powder film and carbon fiber composite subunit of the hybrid excitation high-speed permanent magnet motor rotor of the present invention;

[0022] Figure 5 It is a schematic diagram of the rotor sleeve structure of the hybrid excitation high-speed permanent magnet motor rotor of the present invention;

[0023] Figure 6 This is a schematic diagram of the overall assembly structure of the rotor of the hybrid excitation high-speed permanent magnet motor of the present invention;

[0024] 1-rotating shaft, 2-sintered permanent magnet unit, 3-magnetic powder film and carbon fiber composite unit, 4-rotor sleeve, 5-sintered permanent magnet block, 6-epoxy resin filling body, 7a-carbon fiber layer I, 7b-carbon fiber layer II, 7c-carbon fiber layer III, 8-magnetic powder film layer. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0026] like Figure 1 , Figure 2 , Figure 5 and Figure 6 As shown, a hybrid excitation high-speed permanent magnet motor rotor comprises a rotating shaft 1, a sintered permanent magnet unit 2, a magnetic powder film and carbon fiber composite unit 3 and a rotor sleeve 4; the rotating shaft 1 is located at the innermost side of the high-speed permanent magnet motor rotor, the sintered permanent magnet unit 2 is coaxially sleeved on the outer side of the rotating shaft 1, the magnetic powder film and carbon fiber composite unit 3 is wound on the outer side of the sintered permanent magnet unit 2 by interference fit, a rotor sleeve 4 is arranged on the outer side of the magnetic powder film and carbon fiber composite unit 3, and the rotor sleeve 4 is located at the outermost side of the high-speed permanent magnet motor rotor and is composed of five carbon fiber layers III7c, and the carbon fiber layer III7c is wound on the outer side of the magnetic powder film and carbon fiber composite unit 3 by applying tensile stress;

[0027] The sintered permanent magnet unit 2 includes a sintered permanent magnet block 5, a carbon fiber layer Ⅰ7a and an epoxy resin filler 6. The sintered permanent magnet block 5 is bonded to the outer surface of the rotating shaft 1 to minimize the rotation radius of the sintered permanent magnet block 5, thereby minimizing the centrifugal force during high-speed rotation. Moreover, since the sintered permanent magnet block 5 has a large residual magnetic density, it can provide a large excitation magnetomotive force for the rotor, thereby ensuring that the motor has a high output power density. The gap formed between adjacent sintered permanent magnet blocks 5 is filled with an epoxy resin filler 6. The epoxy resin filler 6 can absorb the deformation stress of the sintered permanent magnet block 5, thereby reducing the risk of excessive local stress on the edge of the sintered permanent magnet block 5 due to temperature or high rotation speed. The epoxy resin filler 6 and the sintered permanent magnet block 5 together form an annular body, and a carbon fiber layer is wound on the outside of the annular body by applying tensile stress. Ⅰ7a, the number of layers of the carbon fiber layer Ⅰ7a is 3, and the winding thickness is 0.45mm. The carbon fiber layer Ⅰ7a provides pre-compression stress for the sintered permanent magnet block 5 to ensure that it is basically not subjected to tensile stress when the rotor runs at high speed, thereby avoiding the sintered permanent magnet block 5 from being damaged due to excessive tensile stress when the rotor rotates at high speed. There are five sintered permanent magnet blocks 5 under each magnetic pole of the high-speed permanent magnet motor rotor, and the pole arc coefficients are the same. The sintered permanent magnet blocks 5 under each magnetic pole are arranged in a circumferential direction in a middle-high and two-end low arrangement, and the epoxy resin filler 6 wraps the four symmetrically arranged sintered permanent magnet blocks 5 under each magnetic pole; the sintered permanent magnet blocks 5 are equal in axial length and unequal in radial thickness. This structural design can make the sinusoidality of the rotor magnetomotive force high, and then make the sinusoidality of the air gap magnetic field high, thereby reducing the high-order harmonic content in the high-speed permanent magnet motor.

[0028] like Figure 3 and Figure 4As shown, the magnetic powder film and carbon fiber composite unit 3 is composed of five magnetic powder film and carbon fiber composite sub-units; the inner layer of the magnetic powder film and carbon fiber composite sub-unit is composed of several layers of magnetic powder film layer 8, and the outer layer is composed of several layers of carbon fiber layer II 7b, and the outer layer is arranged on the outer side of the inner layer; the number of layers of the magnetic powder film layer 8 and the carbon fiber layer II 7b in the magnetic powder film and carbon fiber composite sub-unit is not fixed, and the total number of layers of the magnetic powder film layer 8 and the carbon fiber layer II 7b in the magnetic powder film and carbon fiber composite sub-unit is fixed; since the centrifugal force on the magnetic powder film and carbon fiber composite sub-unit is related to its radius, in order to improve the mechanical strength of the high-speed permanent magnet motor rotor of the present invention, the number of layers of the magnetic powder film layer 8 reaches the maximum value in the magnetic powder film and carbon fiber composite sub-unit with the smallest radius, and the number of layers decreases with the increase of the radius of the magnetic powder film and carbon fiber composite sub-unit, and the carbon fiber layer The number of layers of Ⅱ7b reaches the minimum value in the magnetic powder film and carbon fiber composite subunit with the smallest radius, and the number of layers increases with the increase of the radius of the magnetic powder film and carbon fiber composite subunit; due to the discontinuous distribution of magnetic powder in the magnetic powder film block, the non-conductivity of the film, and the shielding effect of the magnetic powder film and carbon fiber composite unit 3 on high-frequency electromagnetic waves, compared with the traditional high-speed permanent magnet motor rotor, the high-speed permanent magnet motor rotor of the present invention can effectively reduce the eddy current loss in the rotor; in addition, since the magnetic powder film and carbon fiber composite unit 3 contains a large amount of carbon fibers, and the magnetic material in the magnetic powder film is in a magnetic powder state without concentrated stress, the high-speed permanent magnet motor rotor of the present invention can effectively improve the mechanical strength of the rotor; the magnetic powder film layer 8 is formed by uniformly mixing neodymium iron boron (NdFeB) magnetic powder and epoxy resin in a ratio of 7:3 and then curing, and the single layer thickness of the magnetic powder film layer 8 is 0.25mm.

[0029] The rotating shaft 1 in the present invention is a magnetic shaft, which is made of 40CrNiMoA material with good magnetic conductivity; the sintered permanent magnet block 5 uses neodymium iron boron (NdFeB) permanent magnet with high remanence density; the carbon fiber layer I7a, carbon fiber layer II7b and carbon fiber layer III7c are all made of T700 carbon fiber with good tensile properties.

[0030] The high-speed permanent magnet motor rotor of the present invention will be magnetized as a whole by a pulsed strong magnetic field generating device composed of a capacitor bank, a thyristor, a charge and discharge control circuit and a magnetizing head (or a magnetizing coil), thereby forming a number of even-numbered poles, such as 2 poles, 4 poles, 6 poles, etc.

[0031] A method for manufacturing a hybrid excitation high-speed permanent magnet motor rotor comprises the following steps:

[0032] Step 1, uniformly mix NdFeB magnetic powder and epoxy resin in a ratio of 7:3 and solidify to form a magnetic powder film layer block 8; and wind a carbon fiber layer II 7b around the outer side of the magnetic powder film layer block 8 to form a magnetic powder film and carbon fiber composite subunit;

[0033] Step 2, stick the sintered permanent magnet block 5 on the outer circumferential surface of the rotating shaft 1; fill the epoxy resin filler 6 in the sintered permanent magnet block gap formed by adjacent sintered permanent magnet blocks 5, the epoxy resin filler 6 and the sintered permanent magnet block 5 together form an annular body, and wind the carbon fiber layer I7a on the outside of the annular body by applying tensile stress; the magnetic powder film and carbon fiber composite sub-unit prepared in step 1 are successively wrapped around the outside of the carbon fiber layer I7a through interference fit, and the carbon fiber layer III7c is wound on the outside of the magnetic powder film and carbon fiber composite unit 3 by applying tensile stress, and the installation is completed.

Claims

1. A hybrid excitation high-speed permanent magnet motor rotor, characterized in that: It comprises a rotating shaft, a sintered permanent magnet unit, a magnetic powder film and carbon fiber composite unit and a rotor sleeve; the rotating shaft is located at the innermost side of the high-speed permanent magnet motor rotor, the outer side of the rotating shaft is coaxially sleeved with a sintered permanent magnet unit, the outer side of the sintered permanent magnet unit is coaxially sleeved with a magnetic powder film and carbon fiber composite unit, the outer side of the magnetic powder film and carbon fiber composite unit is provided with a rotor sleeve, and the rotor sleeve is located at the outermost side of the high-speed permanent magnet motor rotor and is composed of multiple carbon fiber layers III; The sintered permanent magnet unit comprises a sintered permanent magnet block, a filler and a carbon fiber layer I. The gaps formed between adjacent sintered permanent magnet blocks are filled with the filler. The filler and the sintered permanent magnet block together form an annular body, and the carbon fiber layer I is wound around the outer side of the annular body. The magnetic poles of each high-speed permanent magnet motor rotor are composed of a plurality of sintered permanent magnet blocks. The pole arc coefficients of the plurality of sintered permanent magnet blocks are the same, and the sintered permanent magnet blocks are arranged in a circumferential direction in a high-middle-low arrangement. The sintered permanent magnet blocks have the same axial length and different radial thicknesses. The number of carbon fiber layers III constituting the rotor sleeve is ≤10, and the carbon fiber layers III are all made of carbon fibers with good tensile properties; The magnetic powder film and carbon fiber composite unit is composed of a plurality of magnetic powder film and carbon fiber composite sub-units, the inner layer of the magnetic powder film and carbon fiber composite sub-unit is composed of a plurality of magnetic powder film layers, the outer layer is composed of a plurality of carbon fiber layers II, and the outer layer is arranged on the outer side of the inner layer; the number of layers of the magnetic powder film layer and the number of layers of the carbon fiber layer II in the magnetic powder film and carbon fiber composite sub-unit are not fixed, and the sum of the number of layers of the magnetic powder film layer and the carbon fiber layer II in the magnetic powder film and carbon fiber composite sub-unit is fixed; the number of layers of the magnetic powder film layer is the smallest in the magnetic powder film and carbon fiber composite sub-unit with the smallest radius The maximum value is reached, and the number of layers decreases with the increase of the radius of the magnetic powder film and the carbon fiber composite sub-unit. The number of layers of the carbon fiber layer II reaches the minimum value in the magnetic powder film and the carbon fiber composite sub-unit with the smallest radius, and the number of layers increases with the increase of the radius of the magnetic powder film and the carbon fiber composite sub-unit. The magnetic powder film layer is formed by uniformly mixing magnetic powder and epoxy resin in a certain proportion and then curing. The content of neodymium iron boron magnetic powder in the magnetic powder film layer is ≥60%, and the single layer thickness of the magnetic powder film layer is 0.2mm-0.25mm. The carbon fiber layer II is made of carbon fiber with good tensile properties.

2. The hybrid excitation high-speed permanent magnet motor rotor according to claim 1, characterized in that: The number of magnetic poles of the high-speed permanent magnet motor rotor is an even number; the filler is composed of epoxy resin filler, the number of layers of the carbon fiber layer I is ≤4 layers, the winding thickness is ≤0.8mm, and the carbon fiber layer I is made of carbon fiber with good tensile properties.

3. The hybrid excitation high-speed permanent magnet motor rotor according to claim 1, characterized in that: The sintered permanent magnet block is made of neodymium iron boron permanent magnet with high residual magnetic density; the rotating shaft is a magnetic conductive shaft, which is made of a material with good magnetic conductivity.

4. The method for manufacturing a hybrid excitation high-speed permanent magnet motor rotor according to claim 1, characterized in that: The following steps are involved: Step 1, uniformly mix magnetic powder and epoxy resin in a certain proportion and solidify them to form a magnetic powder film layer block; and wind a carbon fiber layer II on the outside of the magnetic powder film layer block to form a magnetic powder film and carbon fiber composite subunit; Step 2, sticking the sintered permanent magnet block to the outer cylindrical surface of the rotating shaft; filling the epoxy resin filler in the gap between the adjacent sintered permanent magnet blocks, the epoxy resin filler and the sintered permanent magnet block together form an annular body, and winding the carbon fiber layer I on the outside of the annular body by applying tensile stress; the magnetic powder film and carbon fiber composite sub-unit prepared in step 1 are successively wrapped around the outside of the carbon fiber layer I through interference fit, and the carbon fiber layer III is wound on the outside of the magnetic powder film and the carbon fiber composite unit by applying tensile stress, and the installation is completed.

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