A concentrated winding three-phase permanent magnet vernier motor

Abstract

The present invention relates to the technical field of vernier motors, and in particular to a concentrated winding three-phase permanent magnet vernier motor, comprising a rotor and a stator, the rotor and the stator being separated by an air gap; the rotor is composed of a rotor core and a permanent magnet, the permanent magnet is arranged on the outer surface of the rotor in a surface-mounted manner, and two adjacent permanent magnets are arranged in a radial excitation form, and the excitation directions of the two adjacent permanent magnets are opposite; the stator part comprises a stator core and an armature winding. Among them, the stator core adopts an open slot or a semi-open slot structure to modulate the magnetic field, and the armature winding adopts a three-phase design, which is different from the double-layer distributed winding distribution of the traditional three-phase motor under the slot-pole combination. The present invention adopts a double-layer concentrated winding distribution scheme, which can significantly reduce the length of the winding end and greatly improve the power factor of the motor under the premise of slightly reducing the torque performance of the motor. At the same time, the motor of the present invention can reduce the reactive power of the motor system, improve the utilization rate of the DC bus voltage, and has a large application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of vernier motors, and in particular to a concentrated winding three-phase permanent magnet vernier motor. Background Art

[0002] Permanent magnet vernier motors have received extensive attention in the field of electric vehicle direct drive due to their simple structure and high torque density. To obtain a higher torque density, permanent magnet vernier motors need to increase the modulation ratio, mainly from two aspects. One is to increase the number of permanent magnet pole pairs, which will cause the quadrature axis inductance to be significantly higher than that of traditional motors, making the power factor of permanent magnet vernier motors low. This shortcoming causes a large amount of reactive power in the permanent magnet vernier motor system, resulting in a waste of power supply capacity, which seriously limits the application scope of this type of motor.

[0003] In addition, reducing the number of winding pole pairs is also an important means to increase the modulation ratio, but this method often needs to be implemented through the use of distributed windings. Distributed windings will cause the ends of the motor to grow significantly, increasing the size and weight of the motor, while also increasing the motor's copper loss, reducing efficiency, and increasing the difficulty of motor heat dissipation.

[0004] Therefore, how to use winding design methods to reduce the motor's q-axis inductance and increase the motor's power factor while taking into account torque performance is an urgent problem to be solved in the practical application of permanent magnet vernier motors. Summary of the invention

[0005] The purpose of the present invention is to solve the shortcomings of the prior art and propose a concentrated winding three-phase permanent magnet vernier motor. The vernier motor not only has the high torque density performance of traditional permanent magnet vernier motors, but also significantly improves the motor power factor through harmonic winding and three-phase design.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A concentrated winding three-phase permanent magnet vernier motor comprises a stator and a rotor, wherein the stator and the rotor are separated by an air gap;

[0008] The stator is composed of a stator core and an armature winding, and the stator core is an open slot or a semi-open slot;

[0009] The armature winding is divided into three phases, so that in each set of three-phase windings, phase B lags phase A by 40°, and phase C lags phase B by 40°; and the corresponding phases of the three three-phase windings are electromagnetically offset by 120°. The armature winding is wound on the armature teeth in the form of double-layer concentrated winding, and one coil is wound on each armature tooth;

[0010] The rotor is composed of a rotor core and permanent magnets. The permanent magnets are arranged on the surface of the rotor core close to the air gap in a surface-mounted manner. The permanent magnets are radially excited, and the excitation directions of two adjacent permanent magnets are opposite.

[0011] Preferably, the stator core of the stator and the rotor core of the rotor are both formed by laminating silicon steel sheets with high magnetic permeability.

[0012] Preferably, the permanent magnets of the rotor are made of neodymium iron boron or ferrite permanent magnet materials.

[0013] Preferably, the number of pole pairs of the armature winding of the stator is P w , the number of permanent magnet pole pairs of the rotor is P pm , the number of stator teeth is n s , satisfying the following relationship: n s =P w +P pm .

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. The present invention utilizes the magnetic field modulation principle to generate a low-speed effective magnetic field by modulating the permeance change caused by the teeth, which can effectively improve the torque density of the motor.

[0016] 2. The present invention adopts harmonic winding and three-phase design, so that any three-phase winding is unevenly distributed in the electromagnetic field (taking the 18-slot 28-pole motor in the present invention as an example, after the harmonic winding design, phase A leads phase B by 40°, and phase B leads phase C by 40°), but the three three-phase modules are evenly distributed in the electromagnetic field, which ensures the torque pulsation performance while significantly reducing the q-axis inductance and improving the motor power factor.

[0017] 3. The permanent magnet vernier motor of the present invention adopts double-layer concentrated winding, while the traditional winding design adopts a double-layer distributed winding structure under the same slot-pole combination. The present invention significantly shortens the length of the motor end, reduces the motor copper loss, improves the motor efficiency, and helps to alleviate the motor heat dissipation problem.

[0018] 4. The double-layer concentrated winding form adopted by the present invention can significantly reduce the mutual inductance between phases of the motor and improve the fault tolerance performance of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the present invention;

[0020] Figure 2 The winding structure distribution of the present invention and the traditional three-phase winding structure diagram;

[0021] Figure 3 The back-electromotive force waveform diagram of the present invention and the back-electromotive force waveform diagram of the three-phase design under the same structure;

[0022] Figure 4 A torque comparison diagram of the present invention and the traditional structure;

[0023] Figure 5 The power factor variation diagram of the present invention and the traditional structure under different loads. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings, so that those skilled in the art can better understand the advantages and features of the present invention, thereby making a clearer definition of the protection scope of the present invention. The embodiments described in the present invention are only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention.

[0025] Reference Figure 1-Figure 5 , a concentrated winding three-phase permanent magnet vernier motor, comprising a stator 1 and a rotor 2, wherein the stator 1 and the rotor 2 are separated by an air gap 3;

[0026] The stator 1 is composed of a stator core 11 and an armature winding 12, wherein the stator core 11 is an open slot or a semi-open slot;

[0027] The armature winding 12 is divided into three phases, so that in each set of three-phase windings, phase B lags phase A by 40°, and phase C lags phase B by 40°; and the corresponding phases of the three three-phase windings are electromagnetically offset by 120°. The armature winding 12 is wound on the armature teeth 13 in the form of double-layer concentrated windings, and one coil is wound on each armature tooth 13;

[0028] The rotor 2 is composed of a rotor core 21 and permanent magnets 22. The permanent magnets 22 are arranged on the surface of the rotor core 21 close to the air gap 3 in a surface-mounted manner. The permanent magnets 22 are radially excited, and the excitation directions of two adjacent permanent magnets 22 are opposite.

[0029] Specifically, the stator core 11 of the stator 1 and the rotor core 21 of the rotor 2 are both made of laminated silicon steel sheets with high magnetic permeability; the permanent magnet 22 of the rotor 2 is made of neodymium iron boron or ferrite permanent magnet material.

[0030] Specifically, the number of pole pairs of the armature winding 12 of the stator 1 is P w , the number of pole pairs of the permanent magnet 22 of rotor 2 is P pm , the number of stator teeth is n s , satisfying the following relationship: n s =P w +P pm .

[0031] In order to clearly explain the specific implementation of the present invention, the permanent magnet vernier motor structure of the present invention will be described below in conjunction with the accompanying drawings. Figure 1 This is a model of the motor of the present invention. It can be seen that the stator 1 adopts a parallel tooth structure, and the slot shape is an open slot or a semi-open slot, so that the stator teeth can participate in modulation as modulation teeth.

[0032] Figure 2 The armature winding structure diagram of the motor of the present invention and the traditional three-phase winding structure diagram. Among them, a is the winding connection diagram designed by the present invention, and b is the traditional winding connection diagram. It can be seen that the winding structure of the present invention is a double-layer concentrated winding, and the motor has the advantage of short ends; while the traditional three-phase winding structure under the same slot-pole combination adopts a distributed winding with a span of 2, and the winding ends are longer.

[0033] Figure 3 The back electromotive force waveforms of the permanent magnet vernier motor of the present invention and the traditional three-phase permanent magnet vernier motor are given.

[0034] Among them, a is the back EMF diagram of the first set of three-phase windings, b is the back EMF diagram of the second set of three-phase windings, c is the back EMF diagram of the third set of three-phase windings, and d is the back EMF diagram of the traditional three-phase windings. It can be seen that the permanent magnet vernier motor of the present invention has three three-phase windings, and phase A in a single three-phase winding leads phase B by 40°, and phase B leads phase C by 40°. In addition, the three three-phase back EMF phases differ by 120°. The back EMF of the traditional three-phase permanent magnet vernier motor differs by 120°. In addition, the ratio of the single-phase back EMF amplitude of the traditional three-phase permanent magnet vernier motor to the single-phase back EMF amplitude of the present invention is slightly greater than 3. Therefore, the average torque of the traditional three-phase permanent magnet vernier motor is slightly higher than that of the present invention.

[0035] Figure 4 The torque waveforms of the concentrated winding three-phase permanent magnet vernier motor disclosed in the present invention and the conventional three-phase permanent magnet vernier motor are compared. It can be seen that the average torque of the present invention is about 18.0Nm, while the average torque of the conventional three-phase winding is 19.2Nm. The torque of the present invention is slightly reduced, and the reduction ratio is about 6.3%. In addition, the present invention has little effect on torque pulsation.

[0036] Figure 5 The power factor curves of the winding of the present invention and the traditional three-phase winding permanent magnet vernier motor with current are compared. It can be seen that the power factor of the present invention is significantly greater than that of the traditional three-phase winding permanent magnet vernier motor, and as the load increases, the advantage of the present invention in power factor will become more obvious. Under rated current (current effective value is 10A), the power factor of the present invention is 0.91, while the power factor of the traditional three-phase winding permanent magnet vernier motor is only 0.77, and the power factor improvement ratio is 18.8%.

[0037] In summary, the present invention not only has the high torque density performance of the traditional permanent magnet vernier motor, but also has better power factor performance through the three-phase winding design.

[0038] The description and practice disclosed in the present invention are easy to think and understand for ordinary technicians in the technical field, and several improvements and modifications can be made without departing from the principles of the present invention. Therefore, modifications or improvements made without departing from the spirit of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A concentrated winding three-phase permanent magnet vernier motor, characterized in that: It comprises a stator (1) and a rotor (2), wherein the stator (1) and the rotor (2) are separated by an air gap (3); The stator (1) is composed of a stator core (11) and an armature winding (12), and the stator core (11) is an open slot or a semi-open slot; The armature winding (12) is divided into three phases, so that in each set of three-phase windings, phase B lags phase A by 40°, and phase C lags phase B by 40°; and the corresponding phases of the three three-phase windings are electromagnetically offset by 120°. The armature winding (12) is wound on the armature teeth (13) in the form of double-layer concentrated winding, and each armature tooth (13) is wound with a coil. The rotor (2) is composed of a rotor core (21) and permanent magnets (22); the permanent magnets (22) are arranged on a surface of the rotor core (21) close to the air gap (3) in a surface-mounted manner; the permanent magnets (22) are radially excited, and the excitation directions of two adjacent permanent magnets (22) are opposite.

2. A concentrated winding three-phase permanent magnet vernier motor according to claim 1, characterized in that: The stator iron core (11) of the stator (1) and the rotor iron core (21) of the rotor (2) are both formed by laminating silicon steel sheets with high magnetic permeability.

3. The concentrated winding three-phase permanent magnet vernier motor according to claim 1, characterized in that: The permanent magnet (22) of the rotor (2) is made of neodymium iron boron or ferrite permanent magnet material.

4. The concentrated winding three-phase permanent magnet vernier motor according to claim 1, characterized in that: The number of pole pairs of the armature winding (12) of the stator (1) is P w , the number of pole pairs of the permanent magnet (22) of the rotor (2) is P pm , the number of teeth of the stator (1) is n s , satisfying the following relationship: n s =P w +P pm .

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