CN110649729B - A multi-excitation unipolar vernier permanent magnet motor - Google Patents

Abstract

The invention discloses a multi-excitation unipolar vernier permanent magnet motor, belonging to the field of permanent magnet motors. The motor comprises: a stator and a rotor arranged in a nest; the rotor comprises two sections of iron cores spaced along the same axis; It is a hollow cylindrical structure. The hollow cylindrical structure consists of a plurality of iron core units with through holes and protruding teeth. The protruding teeth of each iron core unit are distributed with Halbach magnetic steel arrays, and the adjacent iron core units are separated by magnetic barriers. A connecting magnetic permeable block is inserted between the through holes of the two iron core units, and axially magnetized magnetic steel or a winding into which a circumferential current flows is distributed on the outside of the magnetic permeable block between the two iron core distribution intervals. The invention ensures the excitation magnetic circuit in the axial direction through the single-pole structure, uses the magnetic barrier to block the armature magnetic field in the radial plane, improves the power factor of the motor, reduces the driver capacity, and reduces the application cost; The steel array further increases the excitation magnetic field to increase the motor torque density and improve the motor performance.

Description

A multi-excitation unipolar vernier permanent magnet motor

technical field

The invention belongs to the technical field of permanent magnet motors, and more particularly relates to a multi-excitation unipolar vernier permanent magnet motor.

Background technique

The control system and automation products of industrial robots mainly involve servo motors, reducers, controllers and sensors. The servo motor is the power system of the industrial robot. It is generally installed at the "joint" of the robot and is the "heart" of the robot's movement. At present, the joint drive of the robot is inseparable from the servo system. The more joints, the higher the flexibility and accuracy of the robot, and the more servo motors to be used. The robot has high requirements for the servo system, and must meet the requirements of fast response, high starting torque, large dynamic torque-to-inertia ratio, and wide speed regulation range. And high reliability and stability are required; the electric propulsion system has gradually become the preferred propulsion method for future ships due to its advantages of strong vitality, low noise, low operating cost, and flexible arrangement. The volume weight of the propulsion motor is proportional to its output torque, and ships require a low-speed, high-torque propulsion system, and the volume and weight of the propulsion motor often limit the application of electric propulsion.

In recent years, researchers have developed a type of motor with different numbers of stator and rotor poles. This type of motor has a special magnetic circuit structure. In addition to the magnetic conductivity function, the stator slots also play the role of air-gap magnetic field modulation. Under the action of the stator cogging, the low-speed multi-pole excitation magnetomotive force forms a small-pole high-speed excitation magnetic field on the stator. This special electromagnetic phenomenon makes the external characteristics of this type of motor equivalent to "high-speed permanent magnet motor + magnetic gearbox". With ultra-high torque density, the academic circles refer to this special working principle of the electromagnetic field of the motor as a magnetic field modulation motor. As shown in Figure 1, the vernier permanent magnet motor is one of the typical motor topologies. Compared with the conventional permanent magnet synchronous motor, the vernier permanent magnet motor has the characteristics of high torque density, good back EMF sine, and small torque ripple. Under the same conditions of power supply, material, size and cooling, the vernier permanent magnet motor can The torque density can theoretically reach 2 to 4 times that of conventional permanent magnet motors, and the torque density advantage is very significant, and it has a wide range of applications in industrial robots and electric propulsion systems.

However, the main disadvantage of the existing vernier permanent magnet motor is that its power factor is low, which leads to the need to increase the capacity of the drive converter under the condition of a given output power, thereby increasing the cost and reducing the reliability of system operation. Therefore, how to improve the power factor of the vernier permanent magnet motor has become a key issue for the large-scale application of the motor.

SUMMARY OF THE INVENTION

In view of the defects of the prior art, the purpose of the present invention is to provide a multi-excitation unipolar vernier permanent magnet motor, which aims to solve the problem of low system operation reliability due to low power factor of the existing vernier permanent magnet motor.

In order to achieve the above object, the present invention provides a multi-excitation unipolar vernier permanent magnet motor, comprising: a stator and a rotor arranged in a nest;

The rotor includes a first iron core and a second iron core spaced along the same axis; the first iron core and the second iron core are both hollow cylindrical structures, and the hollow cylindrical structure is composed of a plurality of through holes and protruding teeth. It is composed of iron core units, the protruding teeth of each iron core unit are distributed with Halbeck magnetic steel arrays, and adjacent iron core units are separated by magnetic barriers; a plurality of connecting magnetic conductive blocks are interspersed in the iron core unit through holes of the first iron core and all between the through holes of the iron core unit of the second iron core.

Further, axially magnetized magnetic steel or windings into which circumferential current is introduced are distributed on the outer side of the magnetic conductive block located between the distribution intervals of the first iron core and the second iron core.

Further, the first iron core and the second iron core are axially staggered by an electrical angle of 180 degrees, and the magnetization directions of the Halbach magnetic steel array located outside the first iron core and the Halbach magnetic steel array located outside the second iron core same.

Further, the axial positions of the first iron core and the second iron core are aligned, and the magnetization directions of the Halbach magnetic steel array outside the first iron core and the Halbach magnetic steel array outside the second iron core are opposite.

Further, the number of through holes of the core unit is one or more, and the number of protruding teeth is one or more.

Further, the stator includes stator teeth and stator slots, and is embedded with armature windings.

Further, the stator teeth are single teeth or split teeth.

Further, the vernier permanent magnet motor is a rotary motor or a linear motor.

Through the above technical solutions conceived by the present invention, compared with the prior art, the following beneficial effects can be achieved:

(1) The multi-excitation unipolar vernier permanent magnet motor proposed by the present invention adopts a unipolar structure, and uses the magnetic steel between the two sections of iron cores as an excitation source to form an axial magnetic flux loop; and in the radial plane, due to The rotor core is composed of separated core units, and the magnetic circuit of the armature magnetic field is interrupted, thereby weakening the armature magnetic field and reducing the armature winding inductance on the basis of the decomposition of the permanent magnet magnetic circuit and the armature magnetic circuit. This increases the power factor of the motor.

(2) The multi-excitation unipolar vernier permanent magnet motor proposed by the present invention has Halbach magnetic steel arrays arranged on the outside of the two iron cores. While affecting the blocking effect of the armature magnetic field, the excitation magnetic field is further increased to improve the torque performance of the motor.

Description of drawings

1 is a schematic structural diagram of an existing vernier permanent magnet motor;

2 is a schematic structural diagram of a multi-excitation unipolar vernier permanent magnet motor according to an embodiment of the present invention;

3 is a schematic structural diagram of the first rotor core of a multi-excitation unipolar vernier permanent magnet motor according to an embodiment of the present invention;

4 is a schematic diagram of a multi-excitation unipolar vernier permanent magnet motor magnetic conductive block according to an embodiment of the present invention;

Fig. 5 is the connection schematic diagram of the multi-excitation unipolar vernier permanent magnet motor rotor two-section iron core axially staggered by an electrical angle of 180 degrees in the embodiment of the present invention;

6 is a schematic structural diagram of a rotor of a multi-excitation unipolar vernier permanent magnet motor according to an embodiment of the present invention;

Figure 7 is a schematic diagram of the magnetization direction of the outer Halbach magnetic steel array of the two sections of the iron core when the axes of the two sections of the iron core are staggered upward by an electrical angle of 180 degrees;

8 is a schematic diagram of the connection of the two-section iron cores of the rotor of the multi-excited unipolar vernier permanent magnet motor rotor in an axially aligned upward position according to an embodiment of the present invention;

Fig. 9(a) and Fig. 9(b) are schematic diagrams of the magnetization direction of the Halbach magnetic steel array on the outer side of the two iron cores when the two iron cores are axially aligned in the upward position respectively;

10 is a schematic structural diagram of a second rotor core of a multi-excitation unipolar vernier permanent magnet motor according to an embodiment of the present invention;

FIG. 11 is a schematic diagram of a second rotor core connection according to an embodiment of the present invention;

Fig. 12 is the phasor diagram of the motor under the control mode of I _d = 0, ignoring the voltage drop of the armature winding;

13 is a schematic diagram of a stator structure according to an embodiment of the present invention;

14 is a schematic diagram of another stator structure according to an embodiment of the present invention;

Among them, 1 is the stator, 11 is the stator teeth, 12 is the armature winding, 2 is the rotor, 21 is the first iron core, 22 is the second iron core, 23 is the Halbach magnetic steel array, and 24 is the magnetic steel between the two rotor cores , 25 is the connection of the magnetic conductive block.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

Referring to FIG. 2 , an embodiment of the present invention provides a multi-excitation single-pole vernier permanent magnet motor, including: a stator 1 and a rotor 2 arranged in a nest; the rotor 2 includes a first iron core 21 and a second iron core 21 and second spaced along the same axis Iron core 22; As shown in FIG. 3, the first iron core 21 and the second iron core 22 are both hollow cylindrical structures, and the hollow cylindrical structure is composed of a plurality of iron core units with through holes and protruding teeth, and the adjacent iron core units are composed of magnetic core units. The barriers are separated; as shown in FIG. 4 , a plurality of connecting magnetic conductive blocks 25 are interspersed between the core unit through holes of the first core 21 and the core unit through holes of the second core 22, forming a structure as shown in FIG. 5; each Halbach magnetic steel arrays 23 are distributed among the protruding teeth of each iron core unit, and axially magnetized magnetic steels 24 or magnetic steels 24 passing through a circumferential current are distributed on the outside of the magnetic conductive block located between the distribution intervals of the first iron core and the second iron core. winding to form a complete rotor 2 structure as shown in Figure 6. Among them, the first iron core 21 and the second iron core 22 are staggered by an electrical angle of 180 degrees in the axial direction (as shown in FIG. 5 ), and at the same time, the magnetization direction of the Halbach magnetic steel array outside the two iron cores is the same (the magnetization direction is shown in FIG. 7 ). ), a complete magnetic flux loop can be formed in the axial direction; the first iron core 21 and the second iron core 22 can also be aligned in the axial direction (as shown in FIG. 8 ), and the outer side of the first iron core 21 is magnetized by the Halbach magnetic steel array The direction is shown in Figure 9(a), and the magnetization direction of the Halbach magnetic steel array outside the second core 22 is shown in Figure 9(b). Magnetic flux loop.

The iron core unit shown in FIG. 3 has a through hole and has two protruding teeth; however, the present invention is not limited to this, and the invention does not limit the number of through holes and protruding teeth of the iron core unit. As shown in FIG. 10 , the iron core unit There are two through holes and a protruding tooth, and the connection structure of the two iron cores is shown in Figure 11.

Figure 12 shows the phasor diagram of the motor when the voltage drop of the armature winding is ignored and the control mode of I _d = 0 is adopted, and the expression of the motor power factor is obtained as:

Among them, PF represents the power factor of the motor, E ₀ represents the no-load back EMF, I represents the armature winding current, and X _s represents the synchronous impedance, which is proportional to the armature winding inductance.

It can be seen that the power factor of the motor is related to the no-load back EMF and the synchronous impedance (that is, the armature winding inductance). By increasing the no-load back EMF or reducing the synchronous impedance, the power factor can be increased. The multi-excitation unipolar vernier permanent magnet motor shown in the embodiment adopts a unipolar structure, and the magnetic steel between the two iron cores is used as an excitation source to form an axial magnetic flux loop; while in the radial plane, due to the rotor iron core It is composed of separated iron core units, and the magnetic circuit of the armature magnetic field is interrupted, so that the armature magnetic field is weakened on the basis of the decomposition of the permanent magnetic magnetic circuit and the armature magnetic circuit, and the inductance of the armature winding is reduced, which can increase the The role of high power factor. On this basis, Halbach magnetic steel arrays are arranged on the outside of the two iron cores. Since the Halbach magnetic steel arrays do not need iron cores to form a magnetic flux circuit, this can be done without affecting the blocking of the armature magnetic field. At the same time, the excitation magnetic field is further increased, and the torque performance of the motor is improved.

In the present invention, the stator 1 is of a slot structure, and the armature windings 12 are embedded; wherein, the stator teeth 11 may be a split-tooth structure as shown in FIG. 13 , or a single-tooth structure as shown in FIG. 14 .

The vernier permanent magnet motor proposed by the present invention can be a rotary motor or a linear motor.

Those skilled in the art can easily understand that the above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, etc., All should be included within the protection scope of the present invention.

Claims (7)

1. a multi-excitation unipolar vernier permanent magnet motor, characterized in that, comprising: a nested stator (1) and a rotor (2); The rotor (2) includes a first iron core (21) and a second iron core (22) spaced apart along the same axis; the first iron core (21) and the second iron core (22) are both hollow cylindrical structures, so The hollow cylindrical structure is composed of a plurality of iron core units with through holes and protruding teeth, Halbach magnetic steel arrays (23) are distributed between the protruding teeth of each iron core unit, and adjacent iron core units are separated by a magnetic barrier; The connecting magnetic conductive block (25) is inserted between the iron core unit through hole of the first iron core (21) and the iron core unit through hole of the second iron core (22); Axially magnetized magnetic steel (24) or windings into which circumferential current is introduced are distributed on the outside of the connecting magnetic conductive block between the distribution intervals of the first iron core (21) and the second iron core (22). 2 . The multi-excitation unipolar vernier permanent magnet motor according to claim 1 , wherein the first iron core ( 21 ) and the second iron core ( 22 ) are axially staggered by an electrical angle of 180 degrees, and are located at 180 degrees. 3 . The Halbach magnetic steel array on the outside of the first iron core (21) and the Halbach magnetic steel array on the outside of the second iron core (22) have the same magnetization direction. 3 . The multi-excitation unipolar vernier permanent magnet motor according to claim 1 , wherein the first iron core ( 21 ) and the second iron core ( 22 ) are axially aligned and located in the first iron core ( 21 ) and the second iron core ( 22 ). 4 . The magnetization directions of the Halbach magnetic steel array outside the iron core (21) and the Halbach magnetic steel array located outside the second iron core (22) are opposite. 4 . The multi-excitation unipolar vernier permanent magnet motor according to claim 1 , wherein the iron core unit has one or more through holes and one or more protruding teeth. 5 . 5 . The multi-excitation unipolar vernier permanent magnet motor according to claim 1 , wherein the stator ( 1 ) comprises stator teeth and stator slots, and an armature winding is embedded. 6 . 6 . The multi-excitation single-pole vernier permanent magnet motor according to claim 5 , wherein the stator teeth are single teeth or split teeth. 7 . 7 . The multi-excitation unipolar vernier permanent magnet motor according to claim 1 , wherein the multi-excitation unipolar vernier permanent magnet motor is a rotary motor or a linear motor. 8 .

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