CN111555492B

CN111555492B - Parallel-magnetizing small-rare-earth-combination local Halbach array high-speed permanent magnet motor

Info

Publication number: CN111555492B
Application number: CN202010354317.0A
Authority: CN
Inventors: 许欣; 邓智泉; 张忠明; 庞古才
Original assignee: Nanjing University of Aeronautics and Astronautics
Current assignee: Nanjing University of Aeronautics and Astronautics
Priority date: 2020-04-29
Filing date: 2020-04-29
Publication date: 2021-12-28
Anticipated expiration: 2040-04-29
Also published as: CN111555492A

Abstract

The invention discloses a parallel magnetized rare-earth combined local Halbach array high-speed permanent magnet motor, comprising a stator iron core, a winding, a rotor, a surface-mounted permanent magnet and a protective sleeve. Three-phase windings are arranged in the stator iron core slot; There is a pair of surface-mounted permanent magnets magnetized in parallel with poles. The surface-mounted permanent magnets use a combination of high-remanence NdFeB material and low-remanence ferrite material. Changing the magnetization angle makes some NdFeB and ferrite form a local Halbach array to maintain the original performance of the motor; the protective cover is made of titanium alloy and is installed on the outside of the surface-mounted permanent magnet to increase the structural strength of the rotor and prevent the rotor Disintegrates when rotating at high speed. The invention uses low-cost ferrite material to replace part of the expensive rare-earth permanent magnet material, reduces the cost of the motor, and keeps the performance of the motor unchanged.

Description

Parallel-magnetizing small-rare-earth-combination local Halbach array high-speed permanent magnet motor

Technical Field

The invention relates to a high-speed permanent magnet motor, in particular to a parallel-magnetized small rare earth combined local Halbach array high-speed permanent magnet motor, and belongs to the technical field of high-speed motors.

Background

The research on high-speed motors is becoming one of the research hotspots in the field of electrical engineering. Compared with the common motor, the high-speed motor has higher power density, and the geometric dimension of the high-speed motor is far smaller than that of a medium-low speed motor with the same output power; the rotational inertia is small, and the dynamic response is fast; the high-speed load can be directly driven, a traditional mechanical speed change device is omitted, and loss, mechanical vibration and noise caused by the speed change device are avoided, so that the size of equipment is reduced, the maintenance cost is reduced, and the efficiency and the precision of a transmission system are improved. These advantages of high speed motors have led to their widespread use in a wide variety of applications, such as high speed machine tools, centrifugal compressors, blowers, high pressure water pumps, and the like.

The high-speed motor applied to the field of high-speed transmission mainly comprises a direct-current motor, an alternating-current synchronous motor, a switched reluctance motor, an induction motor and the like. Compared with other types of motors, the permanent magnet synchronous motor has the advantages of high efficiency, reliable operation, high power factor, good control characteristic and the like, so that the permanent magnet motor is widely applied to the field of high-speed transmission.

The Klaus Halbach professor of lawrence berkeli national laboratory in the 80 th 20 th century proposed the concept of Halbach (Halbach) type permanent magnet array first, and unlike the design of the general permanent magnet motor, the Halbach array enhances the magnetic field on one side and weakens the magnetic field on the other side by combining the magnetic steels with different magnetizing directions. The Halbach array has the following excellent characteristics: (1) the Halbach type permanent magnet array can obtain a magnetic field which is distributed in a space according to an ideal sine, and the cogging torque of the motor can be greatly weakened. (2) The Halbach array has the magnetic self-shielding characteristic, and is beneficial to improving the magnetic density in the air gap of the motor, so that the force energy density of the motor is improved, and the volume of the motor is reduced. (3) The Halbach permanent magnet array can improve the efficiency of the motor. Compared with the motor with the conventional permanent magnet radial excitation structure, the Halbach array motor has the advantage that no-load loss is reduced. (4) The Halbach array can reduce the electromagnetic torque pulsation of the motor and reduce the requirements on a motor bearing. But the use of Halbach arrays requires more permanent magnet material.

Rare earth materials represented by neodymium-iron-boron permanent magnets, samarium-cobalt permanent magnets and the like have the advantages of high magnetic energy product and high coercivity, are considered to be permanent magnet materials with the best comprehensive performance at present, and are applied to various fields at present. Along with the proposal of the concept of green environmental protection and the development requirement of new energy technology, the demand of various countries in the world for rare earth materials is obviously increased. The continuous reduction of the storage amount of the rare earth materials and the continuous increase of the demand can cause the instability of the supply chain of the rare earth permanent magnet, the price is continuously increased, and for the rare earth permanent magnet motor, the market background can directly increase the total manufacturing cost of the motor and limit the large-scale application of the motor. Therefore, how to ensure better motor electromagnetic performance while reducing the use amount of rare earth permanent magnet materials becomes a hot point problem in the field of current permanent magnet brushless motors.

In order to alleviate the current situation of rare earth resource shortage and reduce the use amount of rare earth permanent magnet, many scholars aim at a non-rare earth permanent magnet motor. In 2010, massatsugu Takemoto, a scholarer of the university of hokkaido, japan, proposed a novel split axial gap ferrite permanent magnet motor, which fully utilized reluctance torque to achieve the purpose of increasing the total output torque of the motor. French scholars have proposed a spoke type ferrite permanent magnet motor in which the air gap flux of each part is generated by a pair of permanent magnets, thereby achieving the function of magnetic convergence. However, compared with the rare-earth permanent magnet motor, the ferrite permanent magnet motor not only has larger volume, but also inevitably has the defects of torque ripple, noise and the like.

In order to reduce the manufacturing cost of the motor on the premise of keeping the performance of the motor, the invention provides a parallel-magnetized small rare earth combined local Halbach array high-speed permanent magnet motor.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the parallel-magnetizing small rare earth combined local Halbach array high-speed permanent magnet motor is provided, and on the premise of keeping the performance of the motor, the use amount of rare earth permanent magnet materials is reduced, and the manufacturing cost of the motor is reduced.

The invention adopts the following technical scheme for solving the technical problems:

a parallel-magnetizing small rare earth combined local Halbach array high-speed permanent magnet motor comprises a stator core and a rotor, wherein a surface-mounted permanent magnet is arranged on the outer surface of the rotor, the surface-mounted permanent magnet comprises first to sixth neodymium iron boron permanent magnets, a first ferrite permanent magnet and a second ferrite permanent magnet, the first ferrite permanent magnet and the second ferrite permanent magnet are symmetrically arranged around the direct axis of the rotor, the quadrature axis of the rotor penetrates through the centers of the first ferrite permanent magnet and the second ferrite permanent magnet, the stator core is arranged outside the rotor, and a winding is arranged in a slot of the stator core;

the first neodymium iron boron permanent magnet and the second neodymium iron boron permanent magnet are respectively arranged on the upper side and the lower side of the first ferrite permanent magnet, the first neodymium iron boron permanent magnet, the second neodymium iron boron permanent magnet are arranged in a Halbach array form, the fifth neodymium iron boron permanent magnet and the fourth neodymium iron boron permanent magnet are respectively arranged on the upper side and the lower side of the second ferrite permanent magnet, and the fifth neodymium iron boron permanent magnet, the second ferrite permanent magnet and the fourth neodymium iron boron permanent magnet are arranged in a Halbach array form; the sixth neodymium-iron-boron permanent magnet is arranged between the first neodymium-iron-boron permanent magnet and the fifth neodymium-iron-boron permanent magnet, the third neodymium-iron-boron permanent magnet is arranged between the second neodymium-iron-boron permanent magnet and the fourth neodymium-iron-boron permanent magnet, the third neodymium-iron-boron permanent magnet and the sixth neodymium-iron-boron permanent magnet are symmetrically arranged relative to the quadrature axis of the rotor, the direct axis of the rotor penetrates through the centers of the third neodymium-iron-boron permanent magnet and the sixth neodymium-iron-boron permanent magnet, and no gap exists between every two adjacent permanent magnets;

the first to sixth neodymium iron boron permanent magnets, the first ferrite permanent magnet and the second ferrite permanent magnet are magnetized in parallel, the magnetizing directions of the first neodymium iron boron permanent magnet and the fourth neodymium iron boron permanent magnet are the same, the magnetizing directions of the second neodymium iron boron permanent magnet and the fifth neodymium iron boron permanent magnet are the same, the magnetizing directions of the third neodymium iron boron permanent magnet and the sixth neodymium iron boron permanent magnet are the same, and the magnetizing directions of the first ferrite permanent magnet and the second ferrite permanent magnet are the same.

As a preferred scheme of the present invention, the high-speed permanent magnet motor further includes a protective cover, the protective cover is disposed on an outer surface of the surface-mounted permanent magnet, and a gap is formed between the protective cover and the stator core.

In a preferred embodiment of the present invention, the protective sleeve is made of a titanium alloy material.

In a preferred embodiment of the present invention, the number of pole pairs of the high-speed permanent magnet motor is one pair of poles.

As a preferred embodiment of the present invention, the circumferential angles corresponding to the first, second, fifth, and fourth ndfeb permanent magnets are all 40 °, the circumferential angles corresponding to the third, and sixth ndfeb permanent magnets are all 45 °, the circumferential angles corresponding to the first and second ferrite permanent magnets are all 55 °, the first, fourth, and coordinate axes are all 135 ° magnetized, the second, fifth, and coordinate axes are all 45 ° magnetized, the third, sixth, and coordinate axes are all 90 ° magnetized, and the first, second, and coordinate axes are all 90 ° magnetized.

Compared with the prior art, the invention adopting the technical scheme has the following technical effects:

1. the invention uses the segmented neodymium iron boron permanent magnets which are magnetized in parallel at different angles on the straight shaft to replace the whole neodymium iron boron permanent magnet, uses the ferrite permanent magnet on the quadrature shaft to replace the neodymium iron boron permanent magnet and adopts the Halbach array, thereby reducing the consumption of rare earth permanent magnet materials, keeping the air gap flux density of the improved motor unchanged and maintaining the performance of the original motor.

2. The invention can reduce the volume of the rare earth permanent magnet material, reduce the manufacturing cost of the motor and provide wide prospect for the application of the permanent magnet motor in the high-speed field.

Drawings

FIG. 1 is a schematic structural diagram of a parallel-magnetized small rare earth combined local Halbach array high-speed permanent magnet motor.

FIG. 2 is a schematic diagram of the positions, angles and magnetizing directions of the Nd-Fe-B permanent magnet and the ferrite permanent magnet of the motor.

Fig. 3 is a comparison graph of the back electromotive force of the motor of the invention and the traditional parallel magnetizing rare earth permanent magnet motor.

FIG. 4 is a comparison graph of back electromotive force harmonic analysis of the motor of the present invention and a conventional parallel magnetizing rare earth permanent magnet motor.

FIG. 5 is a radial air gap flux density comparison diagram of the motor of the present invention and a conventional parallel magnetizing rare earth permanent magnet motor.

FIG. 6 is a comparison graph of the radial air gap flux density harmonic analysis of the motor of the present invention and a conventional parallel magnetizing rare earth permanent magnet motor.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

As shown in fig. 1, the parallel-magnetized small rare earth combined local Halbach array high-speed permanent magnet motor of the invention comprises first to sixth neodymium iron boron

permanent magnets

11, 12, 13, 14, 15, 16, first to second ferrite

permanent magnets

21, 22, a rotor 3, a protective sleeve 4, a winding 5 and a stator core 6. The surface of the rotor 3 is provided with first to sixth neodymium iron boron permanent magnets and first to second ferrite permanent magnets, the main part of the motor is the neodymium iron boron permanent magnets, the quadrature axis part uses the ferrite permanent magnets, so that the use amount of rare earth permanent magnet materials is reduced, Halbach arrays are adopted for the first and second neodymium iron boron

permanent magnets

11 and 12 and the first ferrite permanent magnet 21, Halbach arrays are adopted for the fourth and fifth neodymium iron boron

permanent magnets

14 and 15 and the second ferrite permanent magnet 22, and the air gap flux density is kept unchanged; the protective sleeve 4 is arranged on the outer side of the permanent magnet, and the protective sleeve 4 is made of a titanium alloy material, so that the structural strength of the rotor can be improved, and the rotor is prevented from being disassembled during high-speed rotation; a stator core 6 is arranged outside the protective sleeve 4; and a three-phase winding 5 is arranged in a slot of the stator core 6. The number of pole pairs of the motor is one pair of poles, and the structure can achieve higher rotating speed.

As shown in fig. 2, the first, second, fourth and fifth ndfeb

permanent magnets

11, 12, 14 and 15 each occupy a 40 ° circumferential angle, the third and sixth ndfeb

permanent magnets

13 and 16 each occupy a 45 ° circumferential angle, and the first and second ferrite permanent magnets each occupy a 55 ° circumferential angle. The first to sixth neodymium-iron-boron

permanent magnets

11, 12, 13, 14, 15, 16 and the first to second ferrite

permanent magnets

21, 22 are all magnetized in parallel. The magnetizing directions of the first neodymium iron boron permanent magnet 11 and the fourth neodymium iron boron permanent magnet 14 are the same, and the magnetizing directions are 135 degrees from the coordinate axis; the magnetizing directions of the second neodymium iron boron permanent magnet 12 and the fifth neodymium iron boron permanent magnet 15 are the same, and the magnetizing directions are 45 degrees with the coordinate axis; the third neodymium iron boron permanent magnet 13 and the sixth neodymium iron boron permanent magnet 16 have the same magnetizing direction and are magnetized at an angle of 90 degrees with the coordinate axis; the first and second ferrite

permanent magnets

21 and 22 are magnetized in the same direction at 90 ° to the coordinate axis.

As shown in fig. 3, when a pair of poles of the conventional rare earth permanent magnet motor are magnetized in parallel, the no-load back electromotive force is similar to a sine wave, the no-load back electromotive force of the rare earth-less combined local Halbach motor is similar to a flat-top wave, the no-load back electromotive force waveforms of the two motors are similar, and it can be seen from fig. 4 that the fundamental wave amplitudes of the two structures are basically equal.

As shown in fig. 5, when a pair of poles of the conventional rare earth permanent magnet motor are magnetized in parallel, the radial air gap flux density of the conventional rare earth permanent magnet motor is similar to a sine wave, while the radial air gap flux density of the local Halbach motor with less rare earth is similar to a flat-top wave, the radial air gap flux density waveforms of the two are similar, and it can be seen from fig. 6 that the fundamental wave amplitudes of the two structures are basically equal.

In order to embody the advantage of the low-rare-earth-combination local Halbach motor in cost, table 1 shows the ratio of the usage amount of the permanent magnet material of the traditional rare-earth permanent magnet motor and the low-rare-earth-combination local Halbach motor, and the usage amount of the neodymium iron boron permanent magnet of the low-rare-earth-combination local Halbach motor is only about 69.44% of that of the traditional rare-earth permanent magnet motor.

TABLE 1

	Rare earth-less combined local Halbach motor	Traditional rare earth permanent magnet motor
			Proportion of Nd-Fe-B	69.44％	100％
Ratio of ferrite	30.56％	0

The invention provides a parallel-magnetizing small-rare-earth-combined local Halbach array high-speed permanent magnet motor, which not only can provide the same electromagnetic performance as that of the traditional rare earth permanent magnet motor, but also greatly reduces the using amount of rare earth permanent magnet materials, and provides wide prospects for the application of the permanent magnet motor in the high-speed field.

The above embodiments are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modifications made on the basis of the technical scheme according to the technical idea of the present invention fall within the protection scope of the present invention.

Claims

1. A parallel magnetized rare earth combined local Halbach array high-speed permanent magnet motor, characterized in that it comprises a stator core (6), a rotor (3), and the outer surface of the rotor (3) is provided with surface-mounted permanent magnets , the surface-mounted permanent magnets include first to sixth NdFeB permanent magnets (11-16), a first ferrite permanent magnet (21), a second ferrite permanent magnet (22), a first iron The oxygen permanent magnet (21) and the second ferrite permanent magnet (22) are symmetrically arranged with respect to the direct axis of the rotor (3), and the quadrature axis of the rotor (3) passes through the first ferrite permanent magnet (21) and the In the center of the second ferrite permanent magnet (22), the stator iron core (6) is arranged outside the rotor (3), and the winding (5) is arranged in the slot of the stator iron core (6);

The first NdFeB permanent magnet (11) and the second NdFeB permanent magnet (12) are respectively arranged on the upper and lower sides of the first ferrite permanent magnet (21), and the first NdFeB permanent magnet ( 11) The first ferrite permanent magnet (21) and the second NdFeB permanent magnet (12) are provided in the form of a Halbach array, the fifth NdFeB permanent magnet (15), the fourth NdFeB permanent magnet (14) ) are respectively arranged on the upper and lower sides of the second ferrite permanent magnet (22), and the fifth NdFeB permanent magnet (15), the second ferrite permanent magnet (22), the fourth NdFeB permanent magnet (22) The magnet (14) is arranged in the form of a Halbach array; the sixth NdFeB permanent magnet (16) is arranged between the first NdFeB permanent magnet (11) and the fifth NdFeB permanent magnet (15), and the third NdFeB permanent magnet (16) is arranged between the first NdFeB permanent magnet (11) and the fifth NdFeB permanent magnet (15). The boron permanent magnet (13) is arranged between the second NdFeB permanent magnet (12) and the fourth NdFeB permanent magnet (14), and the third NdFeB permanent magnet (13) and the sixth NdFeB permanent magnet (13) The magnets (16) are arranged symmetrically with respect to the quadrature axis of the rotor (3), and the straight axis of the rotor (3) passes through the centers of the third NdFeB permanent magnet (13) and the sixth NdFeB permanent magnet (16), phase There is no gap between two adjacent permanent magnets;

The first to sixth NdFeB permanent magnets (11-16), the first ferrite permanent magnet (21), and the second ferrite permanent magnet (22) are all magnetized in parallel, and the first NdFeB permanent magnet (11) and the fourth NdFeB permanent magnet (14) have the same magnetization direction, the second NdFeB permanent magnet (12) and the fifth NdFeB permanent magnet (15) have the same magnetization direction, and the third NdFeB permanent magnet (15) has the same magnetization direction. The permanent magnet (13) and the sixth NdFeB permanent magnet (16) are magnetized in the same direction, and the first ferrite permanent magnet (21) and the second ferrite permanent magnet (22) are magnetized in the same direction;

Circumferential angles corresponding to the first NdFeB permanent magnet (11), the second NdFeB permanent magnet (12), the fifth NdFeB permanent magnet (15), and the fourth NdFeB permanent magnet (14) are 40°, the circumference angles corresponding to the third NdFeB permanent magnet (13) and the sixth NdFeB permanent magnet (16) are both 45°, the first ferrite permanent magnet (21), the second iron The circumferential angles corresponding to the oxygen permanent magnets (22) are all 55°, and the positive direction of the x-axis that defines the rectangular coordinate axis is the same as the orthogonal axis direction of the rotor. The first NdFeB permanent magnet (11), the fourth NdFeB permanent magnet (11), The permanent magnet (14) is magnetized at 135° to the positive direction of the x-axis of the rectangular coordinate axis, and the second NdFeB permanent magnet (12) and the fifth NdFeB permanent magnet (15) are positive to the x-axis of the rectangular coordinate axis. The directions are all magnetized at 45°, the third NdFeB permanent magnet (13), the sixth NdFeB permanent magnet (16) and the positive direction of the x-axis of the Cartesian coordinate axis are magnetized at 90°, and the first ferrite is magnetized at 90°. The permanent magnet (21), the second ferrite permanent magnet (22) and the positive direction of the x-axis of the rectangular coordinate axis are all magnetized at 90°.

2 . The parallel magnetized rare earth combined local Halbach array high-speed permanent magnet motor according to claim 1, characterized in that the high-speed permanent magnet motor further comprises a protective cover (4), and the protective cover (4) is arranged on the surface mount On the outer surface of the permanent magnet, there is a gap between the protective sleeve (4) and the stator core (6).

3 . The parallel magnetized rare-earth combined local Halbach array high-speed permanent magnet motor according to claim 2 , wherein the protective cover ( 4 ) is made of a titanium alloy material. 4 .

4 . The parallel magnetized rare-earth combined local Halbach array high-speed permanent magnet motor according to claim 1 , wherein the number of pole pairs of the high-speed permanent magnet motor is a pair of poles. 5 .