CN107968539B - A permanent magnet segmented switched flux linkage motor - Google Patents

Abstract

A novel switch flux linkage motor with segmented permanent magnets belongs to the technical field of motors; the invention aims to solve the problems that the motor permanent magnet in the prior art has large volume, low utilization rate and influence on the performance of the motor; the permanent magnet motor comprises a stator, a rotor and permanent magnets, wherein the stator is formed by splicing a plurality of U-shaped stator cores which are circumferentially arranged, the side walls of two adjacent stator cores form stator teeth, each stator tooth is embedded with a permanent magnet, the stator teeth form an integral structure through a three-phase armature winding, each permanent magnet is divided into at least two sections in the circumferential direction, and the permanent magnets are divided into at least two sections in the radial direction; the permanent magnet switch flux linkage motor has the advantages of simple structure and convenience in processing and manufacturing, the utilization rate of the permanent magnet can be improved, the cost of the motor is reduced, and the torque ripple and the cogging torque of the permanent magnet switch flux linkage motor are reduced.

Description

A permanent magnet segmented switched flux linkage motor

technical field

A novel switched flux linkage motor belongs to the technical field of motors, and mainly relates to a novel switched flux linkage motor with permanent magnet segments.

Background technique

The traditional permanent magnet switching flux linkage motor is a kind of stator excitation type motor. Both the stator and the rotor adopt a double salient pole structure. The rotor only has an iron core. The permanent magnet is installed on the stator teeth. The structure is relatively simple. The advantages of high torque density and power density can also eliminate the shortcomings of large vibration and noise of switched reluctance motors, which has attracted extensive attention from scholars at home and abroad. The traditional 12/10-pole permanent magnet switching flux linkage motor mainly includes stator, rotor, winding and position sensor. There is no other structure except the rotor core. The 12 permanent magnets are all magnetized along the tangential direction of the circumference, and the magnetizing directions of the two adjacent permanent magnets are opposite. Four windings that are 90 degrees apart in space form a phase.

The traditional permanent magnet switching flux linkage motor has extremely high requirements for production and processing because the stator is isolated by the permanent magnet. And in the design of the traditional permanent magnet switching flux linkage motor, the tooth width, yoke height, slot width, permanent magnet width and rotor core pole width of the U-shaped stator core unit are equal. Using such a design method, the volume of the permanent magnets required when designing a motor with higher power is also larger, which increases the cost of the motor, and at the same time, the utilization rate of the permanent magnet is relatively low. In addition, the shape and structure of the permanent magnets also have a great influence on the performance of the motor. When the motor is running, torque ripple is a very important performance index. Torque ripple mainly includes two parts, namely cogging torque and torque ripple. The cogging torque is a kind of harmonic torque inherent in the permanent magnet motor. The existence of the cogging torque will cause the motor to generate vibration and noise during operation, especially at low speed. The torque ripple is caused by the harmonics of the stator current. It interacts with the back-EMF harmonics, and the back-EMF harmonics are mainly related to the distribution of the excitation magnetic field generated by the permanent magnet in space. Therefore, the shape and structure of the permanent magnet should affect the torque ripple, and reducing the cogging torque and torque ripple is a problem that needs to be considered in the motor design.

SUMMARY OF THE INVENTION

In order to solve the above technical problems, the present invention proposes a new type of switched flux linkage motor with permanent magnet segments, so as to change the distribution of the magnetic field generated by the permanent magnets in the motor, thereby reducing the torque ripple and cogging torque of the motor, At the same time, it also improves the utilization rate of permanent magnets, reduces costs, and facilitates processing.

The object of the present invention is achieved in this way:

A new type of permanent magnet segmented switching flux linkage motor includes a stator, a rotor and a permanent magnet. The stator is assembled from a plurality of circumferentially arranged U-shaped stator cores, and the side walls of two adjacent stator cores form stator teeth. A permanent magnet is embedded on each stator tooth, and the stator tooth forms an integral structure through three-phase concentrated armature windings, that is, the winding pitch is 1, and each permanent magnet wound on each stator tooth is divided into at least Two sections, divided into at least two sections in the radial direction.

Further, a first gap is left between the two sections of permanent magnets in the circumferential direction.

Further, the width of the first gap is at least 0.1 mm.

Further, a second gap is left between adjacent permanent magnets in the radial direction.

Further, the width of the second gap is at least 0.1 mm.

Further, the arrangement of the N poles and the S poles of the permanent magnets in the same stator tooth is the same, and both are magnetized along the circumference tangentially, and the arrangement of the N poles and the S poles of the permanent magnets on the adjacent stator teeth is opposite.

Further, both the stator and the rotor are formed by laminating silicon steel sheets.

Further, the number of stator teeth is 12, and the number of rotor teeth is 10.

Further, the material of the permanent magnet is neodymium iron boron, samarium cobalt or ferrite material.

Compared with the prior art, the present invention has the following beneficial effects. The novel switched flux linkage motor with permanent magnet segments of the present invention has a simple structure, and because the traditional 12 U-shaped stator iron cores can be formed into a whole, it has the advantages of convenient processing. Advantages, but also increase the mechanical strength of the motor. Through finite element analysis, it can be proved that this new type of switched flux linkage motor with permanent magnet segments has the advantages of small torque ripple and small cogging torque. The size needs to be adjusted with reference to motors of different power levels. Since the permanent magnet is divided into several sections, and the distance between the sections of the permanent magnet is appropriately selected, the volume of the permanent magnet can be reduced, the cost can be reduced, and the utilization rate of the permanent magnet can be improved.

Description of drawings

为不分段情况，

为分2段情况，

为分3段，

为分4段；Figure 1 shows the influence on the electromagnetic torque when only the radial segment of the permanent magnet is considered, and the number of segments is different.

For the non-segmented case,

For the 2-stage case,

is divided into 3 sections,

is divided into 4 sections;

为不分段情况，

为分2段情况，

为分3段，

为分4段；Figure 2 shows the effect on cogging torque when only the radial segment of the permanent magnet is considered, and the number of segments is different.

For the non-segmented case,

For the 2-stage case,

is divided into 3 sections,

is divided into 4 sections;

为不分段情况，

为分2段情况，

为分3段，

为分4段；Figure 3 shows the influence on the electromagnetic torque when only the tangential segment of the permanent magnet is considered, and the number of segments is different.

For the non-segmented case,

For the 2-stage case,

is divided into 3 sections,

is divided into 4 sections;

为不分段情况，

为分2段情况，

为分3段，

为分4段情况；Figure 4 shows the influence on cogging torque when only considering the tangential segment of the permanent magnet and the number of segments is different.

For the non-segmented case,

For the 2-stage case,

is divided into 3 sections,

It is divided into 4 sections;

为0mm径向间距时波形，

为0.1mm径向间距时波形，

为0.2mm径向间距时波形；Figure 5 shows the effect of the combination of different radial and tangential distances of the permanent magnets on the average value of the electromagnetic torque when the permanent magnets are segmented.

When the radial spacing is 0mm, the waveform,

When the radial spacing is 0.1mm, the waveform,

Waveform when the radial spacing is 0.2mm;

为0mm径向间距时波形，

为0.1mm径向间距时波形，

为0.2mm 径向间距时波形；Fig. 6 shows the influence of the combination of different radial and tangential distances of the permanent magnets on the torque ripple when the permanent magnets are segmented.

When the radial spacing is 0mm, the waveform,

When the radial spacing is 0.1mm, the waveform,

When the radial spacing is 0.2mm, the waveform;

为0mm径向间距时波形，

为0.1mm径向间距时波形，

为0.2mm 径向间距时波形；Fig. 7 shows the effect of the combination of different radial and tangential distances of the permanent magnets on the cogging torque when the permanent magnets are segmented.

When the radial spacing is 0mm, the waveform,

When the radial spacing is 0.1mm, the waveform,

When the radial spacing is 0.2mm, the waveform;

Figure 8 is the distribution in space of the magnetic field generated by the permanent magnet before the permanent magnet is segmented;

9 is the distribution in space of the magnetic field generated by the permanent magnet after the permanent magnet is segmented;

Figure 10 is a comparison of the electromagnetic torque waveforms of the new type of permanent magnet segmented switching flux linkage motor and the traditional permanent magnet switching flux linkage motor obtained by finite element analysis. In the figure, - is the waveform of the traditional permanent magnet switching flux linkage motor, ----- is the waveform of the new permanent magnet switching flux linkage motor;

Figure 11 is the comparison of the cogging torque waveforms of the new type of permanent magnet segmented switching flux linkage motor and the traditional permanent magnet switching flux linkage motor obtained by finite element analysis. In the figure, - is the waveform of the traditional permanent magnet switching flux linkage motor. , ----- is the waveform of the new permanent magnet switching flux linkage motor;

12 is a schematic cross-sectional view of a novel switched flux linkage motor with permanent magnet segments;

Figure 13 is a stator punching diagram of a novel switched flux linkage motor with permanent magnet segments;

Fig. 14 is a permanent magnet structure diagram of a novel switched flux linkage motor with permanent magnet segments.

Detailed ways

The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

A novel switched flux linkage motor with permanent magnet segments implemented in this embodiment, as shown in FIG. 12 , includes a stator 1 , a permanent magnet 2 , a three-phase concentrated winding 3 and a rotor 4 . Among them, the structure of stator 1 is shown in Figure 13. It is composed of several circumferentially arranged U-shaped stator cores. The side walls of two adjacent stator cores form stator teeth, and each stator tooth is embedded with permanent The magnets and stator teeth form an integral structure through three-phase concentrated armature windings, that is, the winding pitch is 1, which is wound on each stator tooth, and each permanent magnet is divided into at least two sections in the circumferential direction and at least in the radial direction. In the two stages, the stator 1 and the rotor 4 are both formed by laminating silicon steel sheets. In this embodiment, the number of teeth of the stator is 12 and the number of teeth of the rotor is 10.

In the design of the permanent magnet switching flux linkage motor, the tooth width of the U-shaped stator core unit, the height of the yoke, the slot width, the width of the permanent magnet and the pole width of the rotor core are equal; The finite element analysis of the min permanent magnet switched flux linkage motor proves the advantages of the motor with this structure, but different gap adjustments need to be made for motors of different power levels.

The permanent magnets are divided into 2 sections, 3 sections, and 4 sections according to the radial direction. When the effect of spacing is not considered, the effects of different sections on the electromagnetic torque and cogging torque are shown in Figure 1 and Figure 2, respectively. It can be seen from the figure that the radial segment of the permanent magnet has little effect on the electromagnetic torque, torque ripple and cogging torque of the permanent magnet switching flux linkage motor.

When considering the effect of spacing, the permanent magnets are divided into 2 sections according to the radial direction. When the permanent magnets are divided into 3 sections and 4 sections, the effect of different distances of the permanent magnets on the torque performance is that the iron core of the same material as the stator core is embedded between the adjacent permanent magnets. When the number of segments is different, there is a second gap between the adjacent permanent magnets in the radial direction. The influence of the second gap from 0mm to 0.5mm on the electromagnetic torque and cogging torque of the permanent magnet switching flux linkage motor is shown in the table. 1. Through analysis, it is found that with the increase of the second distance, the average value of the electromagnetic torque increases, and after reaching a certain distance, the electromagnetic torque of the motor decreases significantly with the increase of the distance. The torque ripple decreases with the increase of the radial spacing, and the change trend of the cogging torque is consistent with the torque ripple. For the 12/10-pole permanent magnet switching flux linkage motor of the present invention, when the permanent magnets are radially divided into 3 segments and the adjacent spacing is 0.2 mm, the electromagnetic torque is basically unchanged, and the torque ripple and cogging torque are small. , the motor has the best comprehensive torque performance.

Table 1 Influence of permanent magnet radial segment spacing on torque performance

When the effect of spacing is not considered, there is a first gap between adjacent permanent magnets in the tangential direction. The effect of tangential segmentation of permanent magnets on motor torque performance is shown in Figure 3 and Figure 4. Through comparative analysis, it can be obtained It can be concluded that when the permanent magnet is tangentially divided into two sections, the improvement effect on the torque performance of the motor is the best, the electromagnetic torque of the motor is basically unchanged, the torque ripple is reduced, and the cogging torque amplitude is reduced from 141.57mN m. To 140.53mN·m, when it is divided into 3 and 4 tangential sections, the magnitude of the electromagnetic torque decreases, and the torque ripple and cogging torque also increase. It can be concluded that when the permanent magnet is divided into two tangential sections, the torque performance of the motor can be improved, while too many sections will lead to a decrease in torque performance.

The influence of different distances between the two permanent magnet tangential sections on the torque performance of the motor is shown in Table 2. It can be seen from the analysis that with the increase of the distance between the permanent magnets, the torque ripple and cogging torque are greatly reduced. , the electromagnetic torque shows a trend of increasing first and then gradually decreasing. When the electromagnetic torque does not decrease, the torque performance of the motor is optimal when the tangential direction is 2 sections and the distance is 0.5mm.

Table 2 Influence of permanent magnet tangential segment spacing on torque performance

Based on the above comparative analysis, the present invention divides each permanent magnet in the traditional permanent magnet switching flux linkage motor into 6 sections, and in a tangential and radial mixed arrangement, the permanent magnets use the same magnetic conductive material of the stator core between the sections. , so 12 stator core units can form a whole.

The present invention analyzes the average value of electromagnetic torque, torque ripple and cogging torque when the radial and tangential distances are combined, respectively, and the analysis results are shown in Figure 5, Figure 6, and Figure 7, respectively. , the permanent magnet switch flux linkage motor with this structure can greatly improve the torque performance of the motor. When the combination of 0.4mm tangential spacing and 0.1mm radial spacing is selected, the torque ripple decreases from 8.86% to 5.53%, and the amplitude of cogging torque decreases from 135.84mN·m to 96.75mN·m.

To sum up, there are 6 segments of permanent magnets on each stator tooth in this embodiment, and the shape is shown in Figure 14, wherein the arrangement is 3 rows in the radial direction and 2 rows in the tangential direction. The 6 segments of permanent magnets have N poles and S poles. The arrangement is consistent, both are magnetized tangentially along the circumference, and the N-pole and S-pole arrangement of the permanent magnets on the adjacent teeth are opposite. A regular arrangement is carried out, so that the distribution of the magnetic field generated by the permanent magnets in the motor has changed, as shown in Figure 8 and Figure 9, thereby changing the torque ripple of the permanent magnet switching flux linkage motor and adjusting the cogging rotation. moment affects. The electromagnetic torque waveforms of the new structure and the traditional permanent magnet switching flux linkage motor obtained by finite element simulation are shown in Figure 10. It can be clearly seen from the figure that the permanent magnet segmented new switching flux linkage motor of the present invention Torque ripple can be significantly reduced. The cogging torque waveform of the new structure and the traditional permanent magnet switching flux linkage motor obtained by finite element simulation is shown in Figure 11. It can also be concluded that the new switching flux linkage motor of the permanent magnet segment of the present invention can obviously Reduce the cogging torque of the motor.

In this embodiment, the arrangement of the N and S poles of the permanent magnets in the same stator tooth is the same, and they are magnetized along the tangential direction of the circumference. The arrangement of the N and S poles of the permanent magnets on the adjacent stator teeth is opposite. NdFeB, Samarium Cobalt or Ferrite permanent magnet material.

It should be understood that although this specification is described in terms of embodiments, not every embodiment only includes an independent technical solution, and this description in the specification is only for the sake of clarity, and those skilled in the art should take the specification as a whole, and each The technical solutions in the embodiments can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims (5)

1. The utility model provides a permanent magnet sectionalized switch flux linkage motor, includes stator, rotor and permanent magnet, its characterized in that: the stator is formed by splicing a plurality of circumferentially arranged U-shaped stator cores, the side walls of two adjacent stator cores form stator teeth, each stator tooth is embedded with a permanent magnet, the stator teeth form an integral structure through a three-phase armature winding, each permanent magnet is divided into two sections in the circumferential direction, and the permanent magnet is divided into three sections in the radial direction;

a first gap is reserved between the two sections of permanent magnets in the circumferential direction; the first gap width is at least 0.1 mm;

a second gap is reserved between every two adjacent permanent magnets in the radial direction; the width of the second gap is at least 0.1 mm;

and magnetic conductive materials which are the same as the stator iron core are embedded among the sections of the permanent magnet.

2. A permanent magnet segmented switching flux machine according to claim 1, wherein: the arrangement modes of the N poles and the S poles of the permanent magnets in the same stator tooth are consistent and are all magnetized along the circumferential tangential direction, and the arrangement modes of the N poles and the S poles of the permanent magnets on the adjacent stator teeth are opposite.

3. A permanent magnet segmented switching flux machine according to claim 1, wherein: the stator and the rotor are both formed by laminating silicon steel sheets.

4. A permanent magnet segmented switching flux machine according to claim 1, wherein: the number of the stator teeth is 12, and the number of the rotor teeth is 10.

5. A permanent magnet segmented switching flux machine according to claim 1, wherein: the permanent magnet is made of neodymium iron boron, samarium cobalt or ferrite.

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