CN111262358A

CN111262358A - Low-torque ripple magnetic flux reverse motor

Info

Publication number: CN111262358A
Application number: CN202010096025.1A
Authority: CN
Inventors: 李烽; 王凯; 孙海阳; 陈世波; 张旭; 范子涵
Original assignee: Nanjing University of Aeronautics and Astronautics
Current assignee: Nanjing University of Aeronautics and Astronautics
Priority date: 2020-02-17
Filing date: 2020-02-17
Publication date: 2020-06-09

Abstract

The invention discloses a low-torque ripple magnetic flux reverse motor, which comprises a stator and an inner salient pole rotor; the inner salient pole rotor is averagely divided into two sections along the axial direction of the inner salient pole rotor, and two sections of rotor teeth are staggered by one-half pitch; permanent magnets are uniformly arranged on the inner side surfaces of the stator teeth along the circumferential direction of the permanent magnets, the permanent magnets are evenly divided into two sections along the axial direction of the permanent magnets, the two sections correspond to the two sections of rotor teeth respectively, the magnetizing directions of adjacent permanent magnets on the same section are opposite, and the magnetizing directions of axially opposite permanent magnets on different sections are opposite; an air gap is formed between the permanent magnet on the inner side surface of the stator tooth and the inner salient pole rotor; the stator is provided with an armature winding. The invention solves the problem of asymmetric back electromotive force of the traditional flux reversal motor, does not influence the torque density of the motor, and effectively reduces the electromagnetic torque pulsation of the motor.

Description

Low-torque ripple magnetic flux reverse motor

Technical Field

The invention belongs to the field of motors, and particularly relates to a flux reversal motor.

Background

Due to the use of the high-magnetic energy permanent magnet, the permanent magnet motor has the advantages of high torque density, high power density, good weak magnetic performance and high efficiency, and is suitable for running in a full speed range. The stator permanent magnet type magnetic flux reverse motor is widely researched due to the advantages of high torque density, high mechanical strength of the rotor, easiness in heat dissipation of the permanent magnet attached to the inner surface of the stator, and the like, and has wide application prospects in the field of servo driving. However, the traditional flux reversal motor has the problem of asymmetric back electromotive force, and the interaction of the asymmetric back electromotive force and fundamental current causes larger electromagnetic torque pulsation, so that the output electromagnetic torque performance of the motor is deteriorated, and the application of the motor in a driving system is limited.

Disclosure of Invention

In order to solve the technical problems mentioned in the background art, the invention provides a low-torque ripple magnetic flux reversal motor, which solves the problem that the traditional magnetic flux reversal motor has asymmetric counter electromotive force, does not influence the torque density of the motor, and effectively reduces the electromagnetic torque ripple of the motor.

In order to achieve the technical purpose, the technical scheme of the invention is as follows:

a low torque ripple magnetic flux reversal motor comprises a stator and an inner salient pole rotor; the inner salient pole rotor is averagely divided into two sections along the axial direction of the inner salient pole rotor, and two sections of rotor teeth are staggered by one-half pitch; permanent magnets are uniformly arranged on the inner side surfaces of the stator teeth along the circumferential direction of the permanent magnets, the permanent magnets are evenly divided into two sections along the axial direction of the permanent magnets, the two sections correspond to the two sections of rotor teeth respectively, the magnetizing directions of adjacent permanent magnets on the same section are opposite, and the magnetizing directions of axially opposite permanent magnets on different sections are opposite; an air gap is formed between the permanent magnet on the inner side surface of the stator tooth and the inner salient pole rotor; and the stator is provided with an armature winding.

Based on the preferred scheme of the technical scheme, the stator is made of silicon steel sheet laminating or SMC composite soft magnetic materials.

Based on the preferable scheme of the technical scheme, the inner salient pole rotor is made of silicon steel sheets or SMC composite soft magnetic materials.

Based on above-mentioned technical scheme's preferred scheme, the permanent magnet adopts neodymium iron boron permanent magnet or ferrite magnet.

Based on the preferable scheme of the technical scheme, the stator adopts a 12-slot stator, and the armature winding is a three-phase armature winding.

Based on the preferable scheme of the above technical solution, each coil of the three-phase armature winding spans 4 stator slots, and a coil side of the two-phase armature winding is placed in each stator slot.

Based on the preferred scheme of the technical scheme, the three-phase armature winding sequentially comprises an A-phase positive coil, a B-phase negative coil, a C-phase positive coil, an A-phase negative coil, a B-phase positive coil, a C-phase negative coil, an A-phase positive coil, a B-phase negative coil, a C-phase positive coil, an A-phase negative coil, a B-phase positive coil and a C-phase negative coil along the sequence of the coils placed in the stator in the anticlockwise direction.

Adopt the beneficial effect that above-mentioned technical scheme brought:

(1) the invention adopts a segmented rotor structure and a permanent magnet, and the two sections of teeth are staggered by one-half pitch, thereby not only eliminating counter potential even harmonic and solving the problem of asymmetric counter potential, but also reducing electromagnetic torque pulsation, ensuring the position sampling precision of the motor in the control process and improving the running reliability of the motor;

(2) the permanent magnet axial direction average dividing structure is adopted, so that the eddy current loss of the permanent magnet can be reduced, the motor efficiency is improved, the processing and assembly of the permanent magnet can be simplified, the permanent magnet is prevented from being broken in the assembly process, the motor assembly process is simplified, and the production efficiency is improved.

Drawings

FIG. 1 is a schematic cross-sectional view of an electric machine of the present invention;

FIG. 2 is a schematic view of a segmented permanent magnet of the present invention;

FIG. 3 is a schematic view of a segmented rotor of the present invention;

FIG. 4 is a waveform of the no-load back emf of the motor of the present invention;

FIG. 5 is an exploded view of the no-load back emf Fourier of the motor of the present invention;

FIG. 6 is a graph comparing electromagnetic torque of the motor of the present invention with that of a conventional motor;

description of reference numerals: 1. a stator; 2. a permanent magnet; 3. an air gap; 4. an inner salient-pole rotor; 5-16, stator slot number; 17. 18: axially opposed permanent magnets; 19. rotor teeth on the segmented rotor; 20. a segmented rotor; 21. a first motor rotor; 22. a second motor rotor; 23. the pitch of the rotor teeth; 24. one-half rotor pitch.

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 or similar reference numerals refer to the same or similar elements or elements having the same or similar functions. 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. 1-3, the invention relates to a low-torque ripple magnetic flux reversal motor, which comprises a stator 1 and an inner salient pole rotor 4. The inner salient pole rotor 4 is divided into two sections along the axial direction of the inner salient pole rotor, and the two sections of rotor teeth 19 are staggered by one-half pitch, as shown in 23 and 24 in fig. 3. The permanent magnets 2 are uniformly arranged on the inner side surfaces of the stator teeth along the circumferential direction of the stator teeth. The permanent magnet 2 is divided into two

sections

17 and 18 along the self axial direction, the two sections correspond to the two sections of rotor teeth respectively, the magnetizing directions of adjacent permanent magnets on the same section are opposite, and the magnetizing directions of axially opposite permanent magnets on different sections are opposite. An air gap 3 is formed between the permanent magnets on the inner side surfaces of the stator teeth and the inner salient pole rotor. The stator 1 is provided with an armature winding. The motor can be viewed as two separate motors (first and second) in the axial direction, but with the same winding distribution.

The magnetic flux reversal motor structure designed by the invention is the biggest difference from the traditional magnetic flux reversal motor in that: the permanent magnet adopts axial segmentation, two axially opposite magnetizing directions are opposite, and the rotor adopts axial segmentation, and two segments are circumferentially staggered by one-half pitch. Through the structure, counter potential even harmonics of the motor can be eliminated, and electromagnetic torque pulsation of the motor is reduced.

In this embodiment, both the stator and the rotor can be made of silicon steel sheet lamination or SMC composite soft magnetic material. In this embodiment, the stator is configured to have a 12-slot configuration (see 5-16 in FIG. 1) and the rotor is configured to have a 16-tooth configuration. In the embodiment, 36 permanent magnets are uniformly distributed on the surface of the stator teeth to form a permanent magnetic field of the 18-pair-pole stator.

The winding connection of the motor is described below with reference to fig. 1: this embodiment takes as an example a three-phase armature winding, each coil spanning 4 slots and with the coil sides of a two-phase armature winding placed in each slot. To illustrate the connection of the coils in a counterclockwise direction, the coils a + and a-are defined as shown in fig. 1 (phase B and phase C are similar to phase a), and in order to wind the main three-phase armature magnetic field of 2 pairs of motors, the three-phase windings are placed in a circumferential direction as shown in fig. 1, and the coils are distributed on the stator circumference according to a +, B-, C +, a-, B +, C +, a +, B +, C +, and C-.

The invention eliminates counter potential even harmonic, avoids asymmetry of counter potential waveform and reduces torque ripple:

the back electromotive force waveforms of the first motor, the second motor and the whole motor are shown in fig. 4, and the fourier decomposition of the back electromotive force waveform diagram is shown in fig. 5, and it can be seen from the diagram that the back electromotive force waveforms of the first motor and the second motor are asymmetric, whereas the resultant back electromotive force waveforms of the two motors are symmetric. The output torque of the conventional motor and the motor in the patent of the invention is shown in fig. 6, and it can be seen from the figure that the motor can effectively reduce 3 times of torque pulsation of the motor. In addition, although the permanent magnets on the motor stator are axially divided into two sections in average and have opposite polarities, flux leakage cannot be generated between the poles, so that the fundamental wave counter electromotive force of the motor cannot be weakened, namely the torque density of the motor cannot be influenced.

The above embodiments are merely illustrative of the technical idea of the present invention, and the protection scope of the present invention is not limited thereto, for example, the structure of the motor for eliminating back electromotive force of the present invention can be applied to other pole slot matching of a flux reversal motor; the invention is explained by taking a three-phase unit motor as an example, the invention can be expanded to a magnetic flux reversal motor matched with an M-phase pole slot, in addition, the idea can also be expanded to a plurality of motors such as axial magnetic flux and linear motors, and any modification made on the basis of the technical scheme according to the technical idea provided by the invention falls into the protection scope of the invention.

Claims

1. A low torque ripple flux reversing motor, characterized by: comprises a stator and an inner salient pole rotor; the inner salient pole rotor is averagely divided into two sections along the axial direction of the inner salient pole rotor, and two sections of rotor teeth are staggered by one-half pitch; permanent magnets are uniformly arranged on the inner side surfaces of the stator teeth along the circumferential direction of the permanent magnets, the permanent magnets are evenly divided into two sections along the axial direction of the permanent magnets, the two sections correspond to the two sections of rotor teeth respectively, the magnetizing directions of adjacent permanent magnets on the same section are opposite, and the magnetizing directions of axially opposite permanent magnets on different sections are opposite; an air gap is formed between the permanent magnet on the inner side surface of the stator tooth and the inner salient pole rotor; and the stator is provided with an armature winding.

2. The low torque ripple flux opposing motor of claim 1, wherein: the stator is made of silicon steel sheet laminating or SMC composite soft magnetic materials.

3. The low torque ripple flux opposing motor of claim 1, wherein: the inner salient pole rotor is made of silicon steel sheet laminating or SMC composite soft magnetic materials.

4. The low torque ripple flux opposing motor of claim 1, wherein: the permanent magnet adopts a neodymium iron boron permanent magnet or a ferrite permanent magnet.

5. The low torque ripple flux opposing motor of claim 1, wherein: the stator adopts a 12-slot stator, and the armature winding is a three-phase armature winding.

6. The low torque ripple flux opposing motor of claim 5, wherein: each coil of the three-phase armature winding spans 4 stator slots, and coil sides of the two-phase armature winding are placed in each stator slot.

7. The low torque ripple flux reversing electric machine of claim 6, wherein: the three-phase armature winding is sequentially provided with an A-phase positive coil, a B-phase negative coil, a C-phase positive coil, an A-phase negative coil, a B-phase positive coil, a C-phase negative coil, an A-phase positive coil, a B-phase negative coil, a C-phase positive coil, an A-phase negative coil, a B-phase positive coil and a C-phase negative coil along the sequence of the coils placed in the circumferential direction of the stator in an anticlockwise mode.