CN111969824B

CN111969824B - Radial-axial air gap type multiphase transverse flux permanent magnet motor

Info

Publication number: CN111969824B
Application number: CN202010806043.4A
Authority: CN
Inventors: 陈志辉; 陈佳馨; 段津津
Original assignee: Nanjing University of Aeronautics and Astronautics
Current assignee: Nanjing University of Aeronautics and Astronautics
Priority date: 2020-08-12
Filing date: 2020-08-12
Publication date: 2022-10-04
Anticipated expiration: 2040-08-12
Also published as: CN111969824A

Abstract

The invention discloses a radial-axial air gap type multiphase transverse flux permanent magnet motor, wherein multiphase motor units are axially arranged after being staggered by an electric angle of 360/m, each phase of motor unit comprises a stator consisting of a pole shoe-shaped stator core and a pole shoe-shaped permanent magnet, a radial-axial rotor and an armature winding, the permanent magnets are magnetized along the circumferential direction, the magnetization directions of two adjacent permanent magnets are opposite, the armature winding is wound in a groove of the stator, the radial-axial rotor comprises radial teeth, axial teeth and a right-angle yoke, the radial teeth are opposite to the radial outer core of the stator, the axial teeth are opposite to the shoe-shaped tooth parts of the stator core, the radial teeth and the axial teeth are connected through the right-angle yoke, the adjacent radial teeth are separated by a mechanical angle of 360/n degrees, the adjacent axial teeth are separated by a mechanical angle of 360/n degrees, and the radial teeth and the axial teeth under the same pair of poles are separated by a mechanical angle of 180/n degrees. The invention adopts the pole shoe-shaped stator core to increase the relative area of the axial stator and rotor teeth, increase the slot section and increase the number of turns of the winding, thereby increasing the flux linkage.

Description

Radial-axial air gap type multiphase transverse flux permanent magnet motor

Technical Field

The invention belongs to the technical field of transverse flux motors.

Background

The transverse flux motor structure is provided in the beginning of the 80 th 20 th century by Herbert Weh of Germany professor, the stator teeth and the armature windings of the structure are mutually vertical in space, the tooth width and the coil cross section size can be independently designed, and larger torque density can be fundamentally obtained. The transverse flux permanent magnet motor has the advantages of low speed and large torque, small interphase coupling, strong fault-tolerant capability and the like, and is particularly suitable for the field of electric direct drive of wind power generation, electric automobiles, helicopters, ship drives and the like.

The transverse flux permanent magnet motor is developed to the present, various topological structures are provided on the basis of a prototype machine, and the transverse flux permanent magnet motor can be divided into a surface-mounted structure, a magnetic collection structure and a passive rotor structure according to different placement modes of rotor permanent magnets. The surface-mounted structure is simpler, but the utilization rate of the permanent magnet is low; the passive rotor type structure has high reliability, but the use amount of the permanent magnet is increased; the magnetic-gathering structure has large air gap magnetic density and complex structure.

Earlier, 3 megawatt transverse flux permanent magnet motors were developed by the cooperation of royal navy and royce corporation in england for propulsion of a guard ship, and the bilateral structure enables double torque to be obtained when the volume of the motor is increased slightly, but torque generated by the motor with unit effective materials is not increased. Peradeniya, university of Sri Lanka and Royal academy of workers of Stockholm, sweden, have collaboratively developed a three-phase circumferentially aligned transverse flux permanent magnet motor with a rotor embedded in a C-shaped stator core and axially magnetized permanent magnets on a disk rotor, which can achieve higher torque density but low power factor. The Australian Vienna science and technology university provides a magnetic concentration type bilateral stator structure, permanent magnets are embedded in a rotor iron core and magnetized along the circumferential direction, and yoke parts of a stator are pressed by adopting an SMC material.

The research on the transverse flux permanent magnet motor is started late in China, and the research on the transverse flux permanent magnet motor is brought into the national high-tech research and development plan (863 plan) in China. In recent years, many colleges have developed research into transverse flux permanent magnet machines, with some results now being achieved.

In a transverse flux permanent magnet motor provided by Shenyang industry university, a stator core is formed by winding silicon steel sheets, a built-in magnetism-gathering rotor is adopted, and the stator structure can effectively reduce the eddy current loss of the motor and improve the efficiency and the material utilization rate of the motor; a3-phase 5kW prototype is designed and manufactured, and the prototype has high torque density and power factor but does not adopt a bilateral structure, so that the utilization rate of the permanent magnet is low. The subject group of the Qiu Atry professor of Qinghua university provides a novel magnetic-gathering type transverse magnetic flux permanent magnet motor structure, wherein a rotor magnetic pole adopts a three-side wall magnetic-gathering type structure, and a U-shaped stator core is adopted. The structure well plays a role of magnetic concentration of the permanent magnet, improves air gap flux density and simplifies a stator core structure, but the permanent magnet is more in use amount, and the rotor structure is more complex. The Zhejiang university provides a mixed iron core structure based on the three-dimensional magnetic field characteristic of a transverse flux permanent magnet motor, silicon steel is used for stator teeth, SMC is used for a stator yoke, a permanent magnet is placed on a rotor iron core, and the sample machine can obtain higher torque density but does not adopt a magnetism gathering type structure. The university of Hunan Tan proposes a radial magnetizing double-winding transverse flux permanent magnet generator, wherein the motor adopts a single-rotor double-stator structure and is provided with double windings; the rotor is arranged between the two stators, and a pair of permanent magnets is embedded in each rotor iron core, so that the space structure is fully utilized, and the utilization rate of the permanent magnets is improved.

The permanent magnets of the transverse flux permanent magnet motors are all arranged on the rotor, and considering that the vibration and heat dissipation problems of the permanent magnets in some application occasions are serious, the transverse flux permanent magnet motor structure of the passive rotor is provided, but related documents of the passive rotor type are less.

In a passive rotor transverse flux permanent magnet motor provided by professor B.E.Hasubek of Alberta university, canada, permanent magnets and windings are both placed on a stator, the rotor inclines by a polar distance, the structure is convenient to cool, the mechanical impact sensitivity is reduced, the torque density which is the same as that of an active rotor structure is obtained, but the rotor cores of the structure are not connected by a magnetic conductive material, so that the problems of large magnetic flux leakage, low permanent magnet utilization rate and the like are caused. A novel passive rotor transverse magnetic flux permanent magnet motor structure is provided by Kombuquan professor and the like of Harbin university of industry, an armature winding and a permanent magnet are both arranged on a stator, the stator consists of a radial stator ring and an axial stator bridge, and the permanent magnet is attached to the surface of the stator. The motor is convenient to cool, the rotor structure is simple and reliable, higher torque density is provided under the condition that the using amount of the permanent magnet is smaller, but the stator structure is more complex, a magnetism gathering structure is not used, and the air gap magnetic density is lower.

Disclosure of Invention

The purpose of the invention is as follows: the invention provides a radial-axial air gap type multiphase transverse flux permanent magnet motor, which aims to solve the problems of low permanent magnet utilization rate, large magnetic leakage flux, low air gap magnetic density and the like in the prior art.

The technical scheme is as follows: the invention provides a radial-axial air gap type multiphase transverse flux permanent magnet motor which comprises m-phase motor units, wherein the m-phase motor units are sequentially and axially arranged, 360/m electrical angles are staggered between every two adjacent motor units, and m is a positive integer greater than or equal to 3; each phase of motor unit has the same structure and the same size and comprises a stator, a radial-axial rotor and an armature winding; the stator comprises 2n pole shoe-shaped permanent magnets and 2n pole shoe-shaped stator iron cores, the pole shoe-shaped stator iron cores and the pole shoe-shaped permanent magnets are alternately arranged along the circumferential direction to form a fan-shaped annular stator with a groove, and n is a positive integer; in each phase of stator, any one permanent magnet is magnetized along the circumferential direction, and the magnetization direction of the permanent magnet is opposite to that of the adjacent permanent magnet; the radial-axial rotor includes a right-angle yoke, n radial teeth, n first axial teeth, and n second axial teeth; the ith first axial tooth and the ith second axial tooth are respectively arranged on two axial inner sides of the right-angle yoke, the two axial teeth are opposite, the ith radial tooth is arranged on the radial inner side of the right-angle yoke, the radial tooth under the same pair of poles is separated from the first axial tooth by a mechanical angle of 180/n degrees and is separated from the second axial tooth by a mechanical angle of 180/n degrees, in each phase of radial-axial type rotor, adjacent radial teeth are separated by a mechanical angle of 360/n degrees, and adjacent axial teeth are separated by a mechanical angle of 360/n degrees; in any one-phase motor unit, a stator is arranged in a radial-axial rotor, and an armature winding is wound in a groove of the stator.

Furthermore, in the adjacent two-phase motor units, the sum of the electric angle of mutual staggering of the two stators and the electric angle of mutual staggering of the two radial-axial rotors is 360/m.

Further, in the adjacent two-phase motor unit, the adjacent two rotors are connected to each other by a rotor yoke, or a gap exists between the two rotors.

Further, the armature winding adopts a ring-shaped armature winding, and the ring-shaped armature winding comprises two armature windings which are connected in series in an opposite direction.

Furthermore, the pole shoe-shaped stator core is made of soft magnetic composite materials.

Further, the radial-axial rotor is made of soft magnetic composite materials.

Has the advantages that:

1. the invention is a multi-phase structure, which can reduce torque ripple. The stator core adopts the pole shoe-shaped stator core, so that the area of the stator tooth surface facing the air gap is increased, the slot section is increased, the number of turns of the winding is increased, the flux linkage is increased, the counter potential is increased, and the power density is improved when the same current is introduced. The rotor of the invention adopts a radial-axial structure, and main magnetic flux flows through the circumferential outer side surface and the axial end surface of the stator, thereby increasing the magnetic flux of armature winding interlinkage, increasing the electromagnetic torque under the armature ampere-turn and improving the torque density of the motor. In the invention, the adjacent permanent magnets gather magnetism to the middle stator core along the circumferential direction at the same time, and each permanent magnet provides effective magnetomotive force, thereby improving the utilization rate of the permanent magnets compared with the existing passive rotor structure transverse flux motor.

2. The permanent magnet is positioned on the stator, so that the vibration is small and the cooling is easy.

3. If the structure is required to be compact, the rotors of the adjacent two-phase motor units can share the rotor yoke, and because the adjacent two-phase motor units are staggered by a certain electric angle, the magnetic density in the rotor iron core connecting the adjacent two phases is reduced, the thickness of the rotor can be reduced, and the torque density is improved; if structural decoupling is required, the rotors of two adjacent phases may be left with a certain air gap.

4. When the motor operates normally, 2 armature windings are connected in series in an inverted mode, and due to the existence of mutual inductance, the total flux linkage of the windings is weakened, so that the equivalent inductance of the windings is reduced, and the power factor is improved.

5. The stator core and the rotor core are made of soft magnetic composite materials, so that loss between magnetic gaps hardly exists, and eddy current loss inside the stator core and the rotor core is reduced due to the insulating property of the soft magnetic composite materials, so that the efficiency of the motor is improved.

Drawings

Fig. 1 shows a pair of under-pole structures of a rotor yoke shared by adjacent two-phase rotors of a radial-axial air gap type three-phase transverse flux permanent magnet motor according to the present invention.

Fig. 2 shows a pair of under-pole structures with air gaps between adjacent two-phase rotors of the radial-axial air gap type three-phase transverse flux permanent magnet motor of the invention.

Fig. 3 is a cross-sectional view of a pair of poles of the motor of the present invention at maximum flux.

Fig. 4 is a cross-sectional view of a pair of poles after the rotor has rotated 1/2 pole pitch counterclockwise from the flux maximum.

Fig. 5 is a cross-sectional view of a pair of poles after the rotor has rotated counterclockwise by 1 pole pitch from the flux maximum.

Fig. 6 is a stator structure under a pair of poles of the motor of the present invention.

Fig. 7 is a rotor structure under a pair of poles of the motor of the present invention.

Fig. 8 is an equivalent magnetic circuit diagram corresponding to the motor of the present invention when the magnetic flux is maximum.

Fig. 9 is an equivalent magnetic circuit diagram of the motor of the present invention after the rotor rotates counterclockwise by 1 pole pitch from the maximum magnetic flux.

Fig. 10 is a waveform of winding flux as a function of rotor position angle.

Fig. 11 is a waveform of the winding back emf as a function of rotor position angle.

The reference numbers illustrate: 1. a stator core; 2. a permanent magnet; 3. an armature winding; 4. a rotor; 5. the main excitation path when the motor is in the position of fig. 3; 6. the main excitation path when the motor is in the position of fig. 4; 7. the main excitation path when the motor is in the position of fig. 5; 8. a first axial tooth; 9. a second axial tooth; 10. a right angle yoke; 11 radial teeth.

Detailed Description

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an embodiment of the invention and, together with the description, serve to explain the invention and not to limit the invention.

The embodiment provides a radial-axial air gap type multiphase transverse flux permanent magnet motor, as shown in fig. 1 or fig. 2, the motor includes m-phase motor units, the m-phase motor units are sequentially and axially arranged, 360/m electrical angles are staggered between two adjacent motor units, and m is a positive integer greater than or equal to 3; as shown in fig. 3 to 5, each phase motor unit has the same structure and the same size, and includes a stator, a radial-axial rotor, and an armature winding; as shown in fig. 6, the stator is a sector ring stator with a groove, and includes 2n pole shoe-shaped permanent magnets 2 and 2n pole shoe-shaped stator cores 1, where the pole shoe-shaped stator cores 1 and the pole shoe-shaped permanent magnets 2 are alternately arranged along a circumferential direction, n is a pole pair number of a radial-axial air gap type multiphase transverse flux permanent magnet motor, and n is a positive integer; in each phase of stator, any one permanent magnet is magnetized along the circumferential direction, and the magnetization direction of the permanent magnet is opposite to that of the adjacent permanent magnet; the radial-axial rotor comprises, as shown in fig. 7, a right-angle yoke 10, n radial teeth 11, n first axial teeth 8 and n second axial teeth 9; the ith first axial tooth 8 and the ith second axial tooth 9 are respectively arranged on two axial inner sides of the right-angle yoke 10, the two axial teeth are opposite, the ith radial tooth 11 is arranged on the radial inner side of the right-angle yoke 10, the radial teeth under the same pair of poles are respectively separated from the first axial tooth and the second axial tooth by a mechanical angle of 180/n degrees, in each phase of radial-axial type rotor, the adjacent radial teeth 11 are separated by a mechanical angle of 360/n degrees, the adjacent first axial teeth 8 are separated by a mechanical angle of 360/n degrees, and the adjacent second axial teeth 9 are separated by a mechanical angle of 360/n degrees; in any one-phase motor unit, a stator is arranged in a radial-axial rotor, and an armature winding 3 is wound in a groove of the stator.

In this embodiment, two adjacent permanent magnets gather magnetism to the middle stator core along the circumferential direction at the same time, and the magnetic circuit returns to the stator core at the radial outer side through the stator core at the radial outer side, the radial air gap, the radial rotor teeth, the right-angle rotor yoke, the axial rotor teeth, the axial air gap and the stator teeth, and then returns to the stator core at the radial outer side through the stator yoke, so as to form a three-dimensional closed magnetic circuit.

Preferably, in the two-phase motor units adjacent to each other, the sum of the electrical angle by which the two stators are offset from each other and the electrical angle by which the two radial-axial rotors are offset from each other is 360/m.

Preferably, in the adjacent two-phase motor unit, adjacent two rotors are connected to each other by a rotor yoke as shown in fig. 1, or a gap exists between the two rotors as shown in fig. 2.

Preferably, the armature winding is a ring-shaped armature winding, and the ring-shaped armature winding comprises two armature windings which are connected in series in an opposite direction.

Preferably, the pole shoe stator core is made of a soft magnetic composite material.

Preferably, the radial-axial rotor is made of soft magnetic composite material.

The radial-axial air gap type three-phase transverse flux permanent magnet motor is 16 pairs of poles, and three-phase motor units are axially arranged after being staggered by 120 degrees of electrical angle (namely 7.5 degrees of mechanical angle). Each phase motor unit comprises a sector annular stator with grooves, 2 armature windings 3 and a radial-axial rotor 4, wherein the sector annular stator is composed of 32 pole shoe-shaped stator cores 1 and 32 pole shoe-shaped permanent magnets 2. The radial-axial rotor 4 includes 16 radial teeth 11, 16 first axial teeth 8, 16 second

axial teeth

9 and 1 right-angle yoke 10, wherein the radial teeth are opposite to the stator radial outer core, the axial teeth are opposite to the stator core shoe-shaped teeth, the radial teeth and the axial teeth are connected by the right-angle yoke, adjacent radial teeth are separated by 360 degrees electrical angle, i.e. 22.5 (360/16) degrees mechanical angle, adjacent first axial teeth are separated by 360 degrees electrical angle, i.e. 22.5 (360/16) degrees mechanical angle, and the radial teeth under the same pair of poles are separated by 180 degrees electrical angle, i.e. 11.25 (180/16) degrees mechanical angle from the first and second axial teeth; the permanent magnets are magnetized along the circumferential direction, the magnetization directions of two adjacent permanent magnets are opposite, and 2 armature windings are wound in a groove formed after the pole shoe-shaped stator core and the pole shoe-shaped permanent magnets are alternately arranged after being connected in series in an opposite phase mode.

When the motor rotor is in the position of fig. 3, the flux of the armature winding linkages passes axially through the rotor yoke, in which position the flux of the armature winding linkages is at a maximum, and the equivalent magnetic circuit diagram is shown in fig. 8. When the rotor rotates anticlockwise, the relative area of the teeth of the stator and the rotor is reduced, the magnetic circuit reluctance is increased, the magnetic flux linked with the armature winding is reduced, when the rotor rotates anticlockwise to the position shown in figure 4, the axial magnetic flux of the rotor is 0, and the magnetic flux linked with the armature winding is also 0. When the rotor continues to rotate anticlockwise to the position shown in figure 5, the main excitation path is symmetrical to that shown in figure 3, the equivalent magnetic circuit is shown in figure 9, the axial magnetic flux of the rotor is the same as that shown in figure 8, and the direction is opposite, namely phi _ra2 ＝-φ _ra1 . Symbol meaning in fig. 8 and 9: e _PM Is a magnetic potential provided by a permanent magnet, R _PM Is the reluctance of a permanent magnet, R _st Is the stator core reluctance, R, in the

main excitation path

5, 6, or 7 shown in FIG. 3, FIG. 4, or FIG. 5 _rt Is the rotor tooth in the main excitation path 5, 6, or 7Partial magnetic resistance, R _g Is the air gap reluctance, R, in the

main excitation path

5, 6, or 7 _ra Is the rotor yoke axial reluctance in the

main excitation path

5, 6, or 7, phi _ra1 The main excitation path 5 provides the axial magnetic flux of the rotor yoke part, phi _ra2 Is the rotor yoke axial flux provided by the main field path 7.

Through the optimized design, the flux linkage which sinusoidally changes with the rotor angle can be obtained, and the corresponding flux linkage and induced potential waveforms are shown in fig. 10 and fig. 11. If the motor is driven by the prime mover, the generator can generate electricity, and if the current with the same phase is introduced according to the no-load counter electromotive force waveform, the generator can be used as a motor to provide torque for a mechanical load. Theta is the rotor position angle and the figure 3 position corresponds to a rotor position angle of 0 degrees. Tau is the polar pitch angle and pi/16 rad or 11.25 deg. for a 16 pair pole radial-axial air gap three phase transverse flux permanent magnet machine. Phi is the flux of the winding linkage. e is the back electromotive force, e _m Is the back emf peak.

The embodiments of the present invention have been described in detail with reference to the drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention.

Claims

1. The radial-axial air gap type multi-phase transverse flux permanent magnet motor is characterized by comprising m-phase motor units, wherein the m-phase motor units are sequentially and axially arranged, 360/m electrical angles are staggered between every two adjacent motor units, and m is a positive integer greater than or equal to 3; each phase of motor unit has the same structure and the same size and comprises a stator, a radial-axial rotor and an armature winding; the stator is a fan-ring stator with a groove and comprises 2n pole shoe-shaped permanent magnets and 2n pole shoe-shaped stator cores, wherein the pole shoe-shaped stator cores and the pole shoe-shaped permanent magnets are alternately arranged along the circumferential direction, and n is a positive integer; in any phase of stator, any one permanent magnet is magnetized along the circumferential direction of the stator segment, and the magnetization directions of two adjacent permanent magnets are opposite; the radial-axial rotor includes a right angle yoke, n radial teeth, n first axial teeth, and n second axial teeth; the ith first axial tooth and the ith second axial tooth are respectively arranged on two axial inner sides of the right-angle yoke, the two axial teeth are opposite, the ith radial tooth is arranged on the radial inner side of the right-angle yoke, the radial tooth under the same pair of poles is separated from the first axial tooth and the second axial tooth by 180/n degrees of mechanical angle, in each phase of radial-axial type rotor, the adjacent radial teeth are separated by 360/n degrees of mechanical angle, the adjacent first axial teeth are separated by 360/n degrees of mechanical angle, and the adjacent second axial teeth are separated by 360/n degrees of mechanical angle; in any one-phase motor unit, a stator is arranged in a radial-axial type rotor, and an armature winding is wound in a groove of the stator.

2. The radial-axial air gap type polyphase transverse flux permanent magnet motor according to claim 1, wherein in adjacent two-phase motor units, the sum of the electrical angle of mutual misalignment of the two stators and the electrical angle of mutual misalignment of the two radial-axial rotors is 360/m.

3. The radial-axial air gap type multiphase transverse flux permanent magnet motor according to claim 1, wherein in adjacent two-phase motor units, two adjacent radial-axial type rotors are connected with each other by a rotor yoke or a gap exists between the two radial-axial type rotors.

4. The radial-axial air gap multiphase transverse flux permanent magnet motor of claim 1, wherein the armature winding is a toroidal armature winding comprising two armature windings connected in series and in opposition.

5. The radial-axial air gap multiphase transverse flux permanent magnet machine of claim 1, wherein the pole shoe stator core is made of a soft magnetic composite material.

6. The radial-axial air gap type multiphase transverse flux permanent magnet motor according to claim 1, wherein the radial-axial type rotor is made of soft magnetic composite material.