CN102570754A - Permanent-magnet cursor motor for realizing low speed and high torque - Google Patents

Abstract

The invention discloses a permanent magnet vernier motor for low speed and high torque, comprising an outer rotor, a permanent magnet unit, a stator body, a magnetic flux modulation pole unit, a stator slot, a motor shaft, stator teeth, a bearing, a rotor yoke and a winding ; Each permanent magnet unit includes a first permanent magnet, a second permanent magnet and a third permanent magnet, and the magnetization direction of the second permanent magnet is radial magnetization, and the magnetization direction of the first permanent magnet and the third permanent magnet The magnetization direction of the second permanent magnet is symmetrical with the magnetization direction of the second permanent magnet; the stator teeth are fixedly connected with the flux modulation pole unit; each flux modulation pole unit includes a first flux modulation pole, a second flux modulation pole and the third flux modulation pole; the sum of the number of pole pairs n _r of the permanent magnet unit and the number of pole pairs n _p of the winding is equal to the number n _s of the flux modulation poles of all flux modulation pole units. The permanent magnet vernier motor can effectively increase the harmonic component of the magnetic field and the output torque, reduce the magnetic flux density of the rotor yoke, and reduce the core loss.

Description

A permanent magnet vernier motor for low speed and high torque

technical field

The invention relates to a motor, in particular to a permanent magnet vernier motor for low speed and high torque. the

Background technique

The traditional direct drive motor mainly includes the outer rotor of the magnetic gear, the magnetic ring, the inner rotor of the magnetic gear and the motor stator. There is an air gap between the outer rotor of the magnetic gear and the inner rotor of the magnetic gear. There is also a layer of air gap between the motor stator and the inner rotor of the magnetic gear, and there are three layers of air gap in total. The outer rotor permanent magnet vernier motor is a new type of direct drive motor proposed recently, which mainly includes an outer rotor, outer rotor permanent magnets, flux modulation poles and an inner stator. The permanent magnets of the outer rotor adopt ordinary radial magnetization, and the flux modulation poles are placed on the top of the stator teeth. Through the introduction of magnetic flux modulation poles on the stator, the magnetic modulation ring structure in the traditional magnetic gear, the inner rotor and the independent magnetic modulation ring structure in the traditional magnetic gear are omitted, which makes the device structure simpler and solves the problem of The mechanical gear transmission system has problems such as high noise, low efficiency, low transmission accuracy, slow response, and mechanical wear. However, the permanent magnet vernier motor with this structure has large magnetic flux leakage, large core loss, low power factor, and low efficiency.

Contents of the invention

Technical problem: The technical problem to be solved by the present invention is to provide a permanent magnet vernier motor for low speed and high torque, which can effectively improve the harmonic components of the magnetic field and output torque, and reduce the magnetic flux density of the rotor yoke , to reduce core loss.

Technical solution: In order to solve the above technical problems, the present invention adopts a permanent magnet vernier motor for low speed and high torque. The motor includes an outer rotor, a permanent magnet unit, a stator body, a magnetic flux modulation pole unit, a stator slot, a motor shaft, Stator teeth, bearings, rotor yoke and windings; among them, the outer rotor is located outside the stator body, the outer rotor is rotatably connected to the motor shaft through the bearing, and the motor shaft is fixed in the inner cavity of the stator body; the inner surface of the outer rotor is provided with Rotor yoke, each permanent magnet unit is embedded in a rotor yoke; each permanent magnet unit includes a first permanent magnet, a second permanent magnet and a third permanent magnet arranged in sequence along the circumferential direction of the outer rotor, and the second permanent magnet is located at Between the first permanent magnet and the third permanent magnet, and the magnetization direction of the second permanent magnet is radial magnetization, the magnetization direction of the first permanent magnet and the magnetization direction of the third permanent magnet follow the direction of the second permanent magnet The magnetization direction is the axis and is symmetrical to each other; there are radially extending stator teeth with the same length along the circumference of the stator body, and the surface of the stator teeth is wound with windings; one end of each stator tooth is fixedly connected to the stator body, and the other end of each stator tooth is connected to a The magnetic flux modulation pole units are fixedly connected; each magnetic flux modulation pole unit includes a first magnetic flux modulation pole, a second magnetic flux modulation pole and a third magnetic flux modulation pole arranged sequentially along the circumferential direction of the stator body, each flux modulation pole The spacing between adjacent magnetic flux modulation poles in the modulation pole unit is equal, and the spacing is equal to the distance between adjacent magnetic flux modulation pole units; stator slots are formed between adjacent stator teeth; the magnetic flux modulation pole unit and There is a gap between the outer rotors; the sum of the number of pole pairs n _r of the permanent magnet units and the number of pole pairs n _p of the winding is equal to the number n _s of the flux modulation poles of all the flux modulation pole units.

Beneficial effects: compared with the prior art, the present invention has the following beneficial effects:

1. Effectively increase the harmonic components of the magnetic field and the output torque, reduce the magnetic flux density of the rotor yoke, and reduce the core loss. Each permanent magnet unit provided by the present invention includes a first permanent magnet, a second permanent magnet and a third permanent magnet, and the magnetization direction of the second permanent magnet is radial magnetization, and the magnetization direction of the first permanent magnet and the third permanent magnet The magnetization directions of the three permanent magnets take the magnetization direction of the second permanent magnet as an axis, and are symmetrical to each other. The permanent magnet unit adopts Halbach permanent magnet array, and uses finite element optimization to adjust the permanent magnet width ratio and magnetization direction, which can reduce the magnetic flux density of the rotor yoke and increase the air gap magnetic flux density. Therefore, the permanent magnet vernier motor can provide greater effective magnetic field harmonic components and output torque, reduce the size of the rotor yoke, and reduce core loss, thereby improving the efficiency of the motor. At the same time, the permanent magnets of the outer rotor are isolated by the iron core, which blocks the mutual flow of eddy currents in the permanent magnets and reduces the eddy current loss in the permanent magnets of the outer rotor.

2. Compact structure, strong working reliability. The permanent magnet vernier motor provided by the invention saves the mechanical speed change gear box, does not have the mechanical wear, maintenance and noise problems of the gear box, and improves the reliability of the motor operation. At the same time, a magnetic flux modulation pole unit is arranged at one end of the stator teeth, and each magnetic flux modulation pole unit includes three magnetic flux modulation poles, namely a first magnetic flux modulation pole, a second magnetic flux modulation pole and a third magnetic flux modulation pole. The magnetic flux modulation pole unit is used to replace the magnetic modulation ring and an inner rotor of the magnetic gear in the traditional magnetic gear structure, so that the permanent magnet vernier motor of the present invention has a compact structure, smaller volume and lower manufacturing cost. In addition, the rotor in the motor of the present invention adopts high magnetic energy product NdFeB excitation, without slip rings and brushes, and without external power excitation, and has the advantages of simple structure, high power density, high efficiency and good reliability.

3. The motor is easy to adjust and is suitable for various low-speed and high-torque operating environments. In the permanent magnet vernier motor provided by this patent, the ratio of the number of pole pairs n _p of the winding to the number n _r of the pole pairs of the permanent magnet unit is the speed ratio that can be realized by the motor. By properly selecting the pole pair number n _r of the permanent magnet unit and the number n _s of magnetic flux modulation poles, it can be applied to different occasions requiring low-speed direct drive.

Description of drawings

Fig. 1 is an axial sectional view of the present invention.

Fig. 2 is an assembly structure diagram of the stator, the outer rotor and the motor shaft in the present invention.

Fig. 3 is a schematic diagram of the magnetization direction of the permanent magnet unit of the outer rotor part in the present invention, and the direction indicated by the arrow in the figure is the magnetization direction of the permanent magnet.

In the figure there are: outer rotor 1, permanent magnet unit 2, first permanent magnet 201, second permanent magnet 202, third permanent magnet 203, stator body 3, magnetic flux modulation pole unit 4, first magnetic flux modulation pole 401, The second magnetic flux modulation pole 402 , the third magnetic flux modulation pole 403 , the stator slot 5 , the motor shaft 6 , the stator teeth 7 , the bearing 8 , the rotor yoke 9 , and the winding 10 .

Detailed ways

The technical solution of the present invention will be described in detail below in conjunction with the accompanying drawings.

As shown in Figures 1 to 3, a permanent magnet vernier motor for low speed and high torque of the present invention includes an outer rotor 1, a permanent magnet unit 2, a stator body 3, a magnetic flux modulation pole unit 4, and a stator slot 5 , motor shaft 6, stator teeth 7, bearings 8, rotor yoke 9 and winding 10. The outer rotor 1 is located outside the stator body 3 . The outer rotor 1 is rotatably connected to the motor shaft 6 through a bearing 8 . The motor shaft 6 is fixed in the inner cavity of the stator body 3 . The inner surface of the outer rotor 1 is provided with rotor yokes 9 in the circumferential direction, and each permanent magnet unit 2 is embedded in one rotor yoke 9 . Each permanent magnet unit 2 includes a first permanent magnet 201 , a second permanent magnet 202 and a third permanent magnet 203 arranged in sequence along the circumference of the outer rotor 1 . The second permanent magnet 202 is located between the first permanent magnet 201 and the third permanent magnet 203 , and the opposite side walls of adjacent permanent magnets are attached to each other. The magnetization direction of the second permanent magnet 202 is radial magnetization, and the magnetization direction of the first permanent magnet 201 and the magnetization direction of the third permanent magnet 203 are symmetrical to each other with the magnetization direction of the second permanent magnet 202 as an axis. The included angle between the magnetization direction of the first permanent magnet 201 and the magnetization direction of the second permanent magnet 202 is preferably greater than 0 degrees and less than 90 degrees. For example, when the angle between the magnetization direction of the first permanent magnet 201 and the magnetization direction of the second permanent magnet 202 is 45 degrees, the angle between the magnetization direction of the third permanent magnet 203 and the magnetization direction of the second permanent magnet 202 The included angle is also 45 degrees. The width and direction of magnetization of each permanent magnet can be adjusted to achieve the desired power output. Stator teeth 7 extending radially and having the same length are provided along the circumference of the stator body 3 . A winding 10 is wound on the surface of the stator teeth 7 . One end of each stator tooth 7 is fixedly connected to the stator body 3 , and the other end of each stator tooth 7 is fixedly connected to a magnetic flux modulation pole unit 4 . Adjacent stator teeth 7 are equally spaced. Each magnetic flux modulation pole unit 4 includes a first magnetic flux modulation pole 401 , a second magnetic flux modulation pole 402 and a third magnetic flux modulation pole 403 sequentially arranged along the circumferential direction of the stator body 3 . The adjacent magnetic flux modulation poles in each flux modulation pole unit 4 are equally spaced. That is to say, there is a gap between the first magnetic flux modulation pole 401, the second magnetic flux modulation pole 402 and the third magnetic flux modulation pole 403, and the distance between the first magnetic flux modulation pole 401 and the second magnetic flux modulation pole 402 is equal to The distance between the second magnetic flux modulation pole 402 and the third magnetic flux modulation pole 403 is equal. The distance between adjacent magnetic flux modulation pole units 4 is equal, and the distance between adjacent magnetic flux modulation pole units 4 is equal to the distance between adjacent magnetic flux modulation poles in each magnetic flux modulation pole unit 4 . Stator slots 5 are formed between adjacent stator teeth 7 . There is a gap between the magnetic flux modulation pole unit 4 and the outer rotor 1 . The sum of the number of pole pairs n _r of the permanent magnet unit 2 and the number of pole pairs n _p of the winding 10 is equal to the number n _s of the flux modulation poles of all the flux modulation pole units 4, that is, n _s is the number of flux modulation pole units 4 triple the number.

Further, the permanent magnet unit 2 is made of NdFeB material. NdFeB material is the permanent magnet material with the highest magnetic performance at present, and the permanent magnet unit 2 made of NdFeB material can increase the magnetism of the permanent magnet unit 2 . The outer rotor 1 , stator body 3 , stator teeth 7 and flux modulation poles 4 are all made of silicon steel sheet, and the motor shaft 6 is made of non-magnetic material.

The working principle of the permanent magnet vernier motor of the present invention is the space magnetic field modulation principle of the magnetic gear magnetic regulating ring, and the space harmonic is used to transmit energy, and it can be operated in the electric state or in the power generation state.

中的“-”表示调制波磁场与电枢绕组10磁场的旋转方向相反。该调制波磁场与嵌至在转子轭9中的永磁体单元2相互作用，带动外转子1同步旋转。改变通入绕组10电流的频率，从而实现不同的角速度，进而得到不同的外转子1旋转速度-

，实现调速驱动。:

为速度变比，等于永磁体单元2极对数n_r与绕组10极对数n_p之比。因此，该电机可应用在需要低速大转矩的场合，满足在低速时对大转矩输出的要求。 When the motor is running in the electric state, the winding 10 wound on the stator body 3 is supplied with an alternating current of a certain frequency, and the angular velocity of the rotating magnetic field generated by the current in the winding 10 is . After the modulation of the magnetic flux modulation pole unit 4, a modulated wave magnetic field is generated in the air gap between the magnetic flux modulation pole unit 4 and the outer rotor 1, and its rotational angular velocity is - . -

The "-" in represents that the rotation direction of the modulation wave magnetic field is opposite to that of the armature winding 10 magnetic field. The modulated magnetic field interacts with the permanent magnet unit 2 embedded in the rotor yoke 9 to drive the outer rotor 1 to rotate synchronously. Change the frequency of the current passing through the winding 10 to achieve different angular velocities , and then get different rotation speeds of the outer rotor 1 -

, to achieve speed-adjustable drive. :

is the speed ratio, which is equal to the ratio of the number of pole pairs n _r of the permanent magnet unit 2 to the number of pole pairs n _p of the winding 10. Therefore, the motor can be used in occasions that require high torque at low speed, meeting the requirement for high torque output at low speed.

旋转，外转子1产生的旋转磁场，经过磁通调制极单元4的调制作用，产生旋转角速度为

的磁场。该磁场与缠绕在定子本体3上的绕组10产生相对运动，切割绕组10导线产生电能。

:为速度变比，等于永磁体单元2极对数n_r与绕组10极对数n_p之比。通常情况下，永磁体单元2极对数n_r大于绕组10极对数n_p，所以，这可实现电机在低速条件下发电运行，故该电机也可应用在风力发电的场合。 When the motor is running in the state of generating electricity, the outer rotor 1 is at an angular velocity of -

Rotation, the rotating magnetic field generated by the outer rotor 1, through the modulation of the magnetic flux modulation pole unit 4, produces a rotational angular velocity of

magnetic field. The magnetic field generates relative motion with the winding 10 wound on the stator body 3 , and the wires of the winding 10 are cut to generate electric energy.

: is the speed ratio, which is equal to the ratio of the number of pole pairs n _r of the permanent magnet unit 2 to the number of pole pairs n _p of the winding 10. Normally, the number of pole pairs n _r of the permanent magnet unit is greater than the number of pole pairs n _p of the winding 10, so this can realize the motor to generate electricity at low speed, so the motor can also be used in wind power generation.

In the permanent magnet vernier motor with this structure, the permanent magnet unit 2 adopts a special Halbach array, and the finite element is used to optimize and adjust the permanent magnet width ratio and magnetization direction, which can provide greater effective magnetic field harmonic components and output torque, and reduce rotor The magnetic flux density and core loss of the yoke.

Claims (4)

1. A permanent magnet vernier motor for low speed and high torque, characterized in that the motor includes an outer rotor (1), a permanent magnet unit (2), a stator body (3), and a flux modulation pole unit (4) , stator slot (5), motor shaft (6), stator tooth (7), bearing (8), rotor yoke (9) and winding (10); among them, The outer rotor (1) is located outside the stator body (3), and the outer rotor (1) is rotatably connected to the motor shaft (6) through the bearing (8), and the motor shaft (6) is fixed in the inner cavity of the stator body (3) ; The inner surface of the outer rotor (1) is provided with a rotor yoke (9) along the circumference, and each permanent magnet unit (2) is embedded in a rotor yoke (9); each permanent magnet unit (2) includes a rotor yoke (9) along the outer rotor ( 1) The first permanent magnet (201), the second permanent magnet (202) and the third permanent magnet (203) arranged in circumferential order, the second permanent magnet (202) is located between the first permanent magnet (201) and the third permanent magnet between the magnets (203), and the magnetization direction of the second permanent magnet (202) is radial magnetization, the magnetization direction of the first permanent magnet (201) and the magnetization direction of the third permanent magnet (203) are The magnetization direction of the two permanent magnets (202) is the axis and is symmetrical to each other; radially extending stator teeth (7) with the same length are arranged along the circumference of the stator body (3), and the stator teeth (7) are wound with windings (10) on the surface; One end of each stator tooth (7) is fixedly connected to the stator body (3), and the other end of each stator tooth (7) is fixedly connected to a magnetic flux modulation pole unit (4); each magnetic flux modulation pole unit (4) includes The first magnetic flux modulation pole (401), the second magnetic flux modulation pole (402) and the third magnetic flux modulation pole (403) arranged in the circumferential direction of the stator body (3), each magnetic flux modulation pole unit ( 4) The spacing between adjacent magnetic flux modulation poles is equal, and the spacing is equal to the distance between adjacent magnetic flux modulation pole units (4); stator slots (5) are formed between adjacent stator teeth (7) ); there is a gap between the magnetic flux modulation pole unit (4) and the outer rotor (1); the sum of the pole pair number n _r of the permanent magnet unit (2) and the pole pair number n _p of the winding (10) is equal to all flux modulation poles The number n _s of the magnetic flux modulation poles of the unit (4). 2. The permanent magnet vernier motor for low speed and high torque according to claim 1, characterized in that, the permanent magnet unit (2) is made of NdFeB material. 3. The permanent magnet vernier motor for low speed and high torque according to claim 1, characterized in that, the outer rotor (1), stator body (3), stator teeth (7) and flux modulation poles (4) are all made of silicon steel sheets, and the motor shaft (6) is made of non-magnetic materials. 4. The permanent magnet vernier motor for low speed and high torque according to claim 1, characterized in that, in the permanent magnet unit (2), the magnetization direction of the first permanent magnet (201) is the same as that of the second permanent magnet (201). The included angle of the magnetization direction of the permanent magnet (202) is greater than 0 degrees and less than 90 degrees.

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