CN102904404A - A Coreless Axial Field Brushless DC Motor Based on Halbach Structure - Google Patents

Abstract

The invention discloses a Halbach-structure-based iron-core-free axial magnetic field brushless direct-current electromotor which comprises a stator iron-core-free armature disc, a permanent magnet, a rotor disc, a shaft, a bearing and a rotor outer shell, wherein two symmetrical rotor discs are arranged at two sides of the stator iron-core-free armature disc; the stator iron-core-free armature disc and the rotor disc are installed on the shaft; the shaft is installed in the rotor outer shell through the bearing; the permanent magnet is pasted on the rotor disc, and is pasted on the inner surface of the rotor outer shell; a Halbach magnet structure with axial magnetizing and tangential magnetizing is adopted for the permanent magnet, and an enclosed magnetic circuit is formed automatically; and a soft magnetic material is placed at the middle of the permanent magnet with tangential magnetizing. According to the invention, on the basis that more permanent magnets are not used, flux density with great air clearance can be obtained, and are is in sine distribution; the output torque is high; the torque density is large; the efficiency is high; the structure is simple; the assembly is simple; and the Halbach-structure-based iron-core-free axial magnetic field brushless direct-current electromotor is suitable for relevant driving occasions with compact structures for electric automobile hub motors and the like.

Description

A Coreless Axial Field Brushless DC Motor Based on Halbach Structure

technical field

The invention relates to the technical field of motors, in particular to a coreless axial magnetic field brushless DC motor based on a Halbach structure.

Background technique

Environmental pollution and energy shortage are important issues in today's world, which are related to the improvement of human living environment. With the rapid development of the automobile society, environmental problems such as air pollution within cities and global carbon dioxide emissions have attracted widespread attention. In order to solve the above problems, research and development of energy-saving, environment-friendly and safe vehicles is the only way to achieve sustainable development. Among them, electric vehicles have attracted much attention due to their advantages in low pollution, high fuel economy, high efficiency, and flexibility in driving. In the field of electric vehicles, the structure of direct drive system using in-wheel motors has increasingly become a development direction, and in-wheel motors have gradually become a research hotspot in the field of electric vehicles. Different from the structure of the traditional single-motor centralized drive electric vehicle, the direct drive means that the motor is directly installed in the wheel, and each wheel is equipped with a motor, called a hub motor, which directly drives the wheel to drive the car. The main advantage of this structure is that the gearbox and mechanical differential are eliminated, and the components of the drive chain are reduced, thereby reducing the weight of the entire drive chain and improving the reliability and efficiency of the entire system. However, since the gear is eliminated, the torque for driving the wheel shaft must be generated by the electric motor, and the volume and weight of the electric motor will increase. Therefore, the main challenge of the direct drive system is to make the volume and weight of the hub motor installed in the wheel as small as possible, and a balance should be made between the volume, weight and power of the motor.

In view of the characteristics and requirements of the hub motor itself, the axial magnetic field coreless permanent magnet synchronous motor is a good choice. In the prior art, there is also an axial magnetic coreless permanent magnet synchronous motor, which can reduce the mass of the motor, eliminate cogging torque and core loss, but after the stator adopts an ironless core, the effective air gap becomes larger, and the air gap flux density Not high, resulting in a relatively low torque density of the motor.

In order to improve the air gap flux density, permanent magnet motors using Halbach type array permanent magnets are gradually being applied. In the existing axial magnetic coreless permanent magnet motor based on the Halbach structure, in order to obtain a sinusoidally distributed air gap flux density, the magnetization directions of the Halbach array permanent magnets must be varied, which will inevitably increase the manufacturing cost of the permanent magnets, thereby increasing the overall motor capacity. cost, reducing the cost performance.

Contents of the invention

In order to overcome the deficiencies in the prior art, the present invention provides a Halbach magnet structure with less permanent magnet consumption, low cost, light weight, no iron loss, high efficiency, greatly increased air gap magnetic density, and sinusoidal distribution of the axial direction of the Halbach magnet structure. Field Ironless Permanent Magnet Brushless DC Motor.

The technical solution adopted by the present invention is: a coreless axial magnetic field brushless DC motor based on Halbach structure, including a stator coreless armature disc, a permanent magnet, a rotor disc, a shaft, a bearing and a rotor housing;

There are two symmetrical rotor disks on both sides of the stator coreless armature disk, the stator coreless armature disk and the rotor disk are installed on the shaft, the shaft is installed in the rotor shell through the bearing, and the permanent rotor disk is pasted on the rotor disk. Magnet, the permanent magnet is pasted on the inner surface of the rotor shell;

The permanent magnet adopts the Halbach magnet structure of axial magnetization and tangential magnetization, which can form a closed magnetic circuit by itself, saves the rotor back iron, and reduces the weight of the rotor. The tangentially magnetized permanent magnet is placed in the middle of a soft magnetic The material can reduce the amount of permanent magnets and reduce the manufacturing cost of the motor under the premise of ensuring that the air-gap flux density with sinusoidal distribution can be produced without weakening the air-gap flux density. Each magnetic pole on each rotor disc is composed of four parts: axial A magnetized permanent magnet, a soft magnetic material and two tangentially magnetized permanent magnets.

As a preference, the coreless armature disk of the stator adopts a non-overlapping concentrated winding type, the winding terminal part is shorter, the consumption is less, and the copper consumption is less, and the structure of this winding type is simple, and the processing is convenient.

Preferably, the rotor shell is made of non-magnetic material with high mechanical strength.

Preferably, the permanent magnet is made of NdFeB material with high magnetic energy product.

The stator of the invention adopts an iron-coreless structure, which can eliminate the cogging torque and core loss, eliminate the axial magnetic force between the stator and the rotor, and facilitate assembly. By selecting the appropriate rotor permanent magnet material, the size of the soft magnetic material, and the appropriate placement position, a sinusoidally distributed magnetic field waveform can be generated to weaken the harmonic component.

The present invention proposes an axial magnetic field coreless brushless DC motor with a Halbach magnet structure. The motor is an improvement to the existing Halbach structure permanent magnet motor. The Halbach permanent magnet array only adopts two methods of axial magnetization and tangential magnetization. For magnets in two directions, soft magnetic materials are added between two tangentially magnetized magnets. On the basis of ensuring a certain air gap flux density, the amount of permanent magnets is reduced, the cost of the motor is reduced, and the weight of the rotor is reduced, thereby improving the rotation of the motor. moment density. By selecting the appropriate permanent magnet material, soft magnetic material size and their placement position, the sine of the air gap magnetic density can be improved and the harmonic component can be weakened.

Beneficial effects of the present invention: 1) The stator plate adopts the coreless structure, which eliminates the cogging torque and core loss, improves the motor efficiency, and reduces the quality of the motor; 2) The magnetic steel plate adopts the combination of axial and tangential Halbach The permanent magnet array saves the rotor back iron, reduces the mass of the rotor, and improves the air gap magnetic density, thereby increasing the output torque of the motor and increasing the torque density; 3) In the adjacent two tangentially magnetized The soft magnetic material is embedded in the middle of the permanent magnet, which reduces the amount of high-priced NdFeB permanent magnets and reduces the cost of the motor; 4) By reasonably arranging the size and position of the permanent magnet material and soft magnetic material, the On the basis, it is easy to obtain a sinusoidally distributed air gap flux density, which weakens harmonics and reduces torque ripple.

Description of drawings

Fig. 1 is the structural representation of motor embodiment of the present invention;

Fig. 2 is a sectional view of Fig. 1;

Fig. 3 is an expanded view of the internal structure of the motor at the average radius of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figures 1 and 2, an ironless axial field brushless DC motor based on the Halbach structure includes a stator ironless armature disc 1, a permanent magnet 2, a rotor disc 3, a shaft 5, a bearing 4 and a rotor housing 6 The two sides of the stator coreless armature disc 1 are provided with two symmetrical rotor discs 3, the stator coreless armature disc 1 and the rotor disc 3 are installed on the shaft 5, and the shaft 5 is installed in the rotor shell 6 through the bearing 4 , the rotor disk 3 is pasted with a permanent magnet 2, and the permanent magnet 2 is pasted on the inner surface of the rotor housing 6; the permanent magnet 2 adopts the Halbach magnet structure of axial magnetization 7 and tangential magnetization 8, forming a closed In the magnetic circuit, a soft magnetic material 9 is placed in the middle of the permanent magnet 2 which is tangentially magnetized 8 . As shown in FIG. 3 , each magnetic pole on each rotor disk 3 is composed of four parts: a permanent magnet magnetized axially 7 , two permanent magnets magnetized tangentially at 90 degrees and a piece of soft magnetic material 9 . On the same rotor disc, the axially magnetized permanent magnets 7N and S are separated, and the magnetic flux is along the axial direction, and the axially magnetized N-pole permanent magnet 7 on a magnetic steel disc—air gap—stator coreless armature disc 1—Axially magnetized N pole permanent magnet on another magnetic steel plate—tangentially magnetized permanent magnet, soft magnetic material—axially magnetized S pole permanent magnet—air gap—axially magnetized S pole permanent magnet—cut Magnetizing permanent magnets, soft magnetic materials - axially magnetizing N-pole permanent magnets, thus forming a closed loop, without the need for rotor back iron to form a closed magnetic circuit.

The stator coreless armature disk 1 adopts the non-overlapping concentrated winding type, which is directly injection molded from the non-overlapping concentrated winding. The windings are placed symmetrically, and lead wires are provided for applying three-phase alternating current. The rotor shell 6 is made of non-magnetic material with high mechanical strength, and the permanent magnet 2 is made of NdFeB material with high magnetic energy product.

It should be pointed out that those skilled in the art can make some improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention. All components that are not specified in this embodiment can be realized by existing technologies.

Claims (4)

1. A coreless axial magnetic field brushless DC motor based on Halbach structure, characterized in that: comprising stator coreless armature disc, permanent magnet, rotor disc, shaft, bearing and rotor housing; There are two symmetrical rotor disks on both sides of the stator coreless armature disk, the stator coreless armature disk and the rotor disk are installed on the shaft, the shaft is installed in the rotor shell through the bearing, and the permanent rotor disk is pasted on the rotor disk. Magnet, the permanent magnet is pasted on the inner surface of the rotor shell; The permanent magnet adopts the Halbach magnet structure of axial magnetization and tangential magnetization, and forms a closed magnetic circuit by itself. The soft magnetic material is placed in the middle of the tangential magnetization permanent magnet, and each magnetic pole on each rotor disk is composed of four Partial composition: axially magnetized permanent magnet, soft magnetic material and two tangentially magnetized permanent magnets. 2 . The coreless axial magnetic field brushless DC motor based on Halbach structure according to claim 1 , wherein the coreless armature disc of the stator adopts a non-overlapping concentrated winding type. 3 . 3 . The coreless axial magnetic field brushless DC motor based on Halbach structure according to claim 1 , wherein the rotor shell is made of non-magnetic material with high mechanical strength. 4 . 4. A coreless axial magnetic field brushless DC motor based on Halbach structure according to claim 1, characterized in that: said permanent magnet is made of NdFeB material with high energy product.

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