CN209948818U - Rotor assembly and alternating-pole motor - Google Patents

Abstract

The application provides a rotor assembly and a consequent pole motor. This rotor subassembly includes rotor core (1), rotor core (1) includes the permanent magnetism pole and the alternative pole of arranging in turn along circumference, the permanent magnetism pole includes mounting groove (2), install permanent magnet (3) in mounting groove (2), permanent magnet (3) are same polarity towards the polarity of rotor core (1) outer peripheral edges, the both ends of mounting groove (2) are provided with second air groove (5) respectively, second air groove (5) include the groove body and follow first extension (6) and second extension (7) that the groove body extended to the magnetic pole central line, first extension (6) and second extension (7) set gradually and form radial thickness degressive ladder groove. According to the rotor assembly, the problem of torque pulsation increase caused by back electromotive force harmonic waves of the alternating-pole motor can be effectively solved, the back electromotive force harmonic content is obviously reduced, and the motor performance is improved.

Description

Rotor assembly and alternating-pole motor

Technical Field

The application relates to the technical field of motors, in particular to a rotor assembly and an alternating-pole motor.

Background

The number of the permanent magnets used by the alternating-pole permanent magnet synchronous motor is only half of that of the permanent magnets of the traditional permanent magnet synchronous motor, so that the permanent magnets are utilized more fully, the use amount of the permanent magnets can be reduced remarkably, and the cost of the motor is reduced.

However, the special magnetic circuit structure also brings many problems, including the problems of output torque reduction caused by reduction of the use amount of the permanent magnets and torque fluctuation increase caused by asymmetry of adjacent magnetic pole structures, and further popularization and application of the alternating-pole motor are limited.

Some alternating-pole motors in the prior art improve torque fluctuation by optimizing pole arc coefficients, mainly aiming at torque fluctuation caused by cogging torque, but have no effect on torque pulsation caused by non-sinusoidal back electromotive force, so that the alternating-pole motors have poor effect on the problem of torque pulsation increase caused by rich back electromotive force harmonic content.

SUMMERY OF THE UTILITY MODEL

Therefore, the technical problem to be solved by the present application is to provide a rotor assembly and a consequent pole motor, which can effectively improve the problem of torque ripple increase caused by the counter electromotive force harmonic of the consequent pole motor, significantly reduce the counter electromotive force harmonic content, and improve the motor performance.

In order to solve the above problem, the application provides a rotor subassembly, including rotor core, rotor core includes the permanent magnetism pole and the alternative pole of arranging in turn along circumference, the permanent magnetism pole includes the mounting groove, install the permanent magnet in the mounting groove, the polarity of permanent magnet towards rotor core outer peripheral edges is same polarity, the both ends of mounting groove are provided with the second air tank respectively, the second air tank includes the groove body and follows first extension and the second extension of groove body to the extension of magnetic pole central line, first extension and second extension set gradually and form the degressive ladder groove of radial thickness.

Preferably, the first extension portion and the second extension portion are provided on a side of the slot body near the outer circumference of the rotor core.

Preferably, the magnetic pole center line is provided with a first air slot, and the distance between the second air slot and the outer periphery of the rotor core is smaller than the distance between the first air slot and the outer periphery of the rotor core.

Preferably, an included angle formed by the side walls, close to the center line of the magnetic pole, of the two first extension portions located in the same permanent magnetic pole is a21, and an included angle formed by the side walls, close to the center line of the magnetic pole, of the two second extension portions located in the same permanent magnetic pole is a22, wherein a22/a21 is 0.7-0.9.

Preferably, an included angle formed between the side walls, close to the center line of the magnetic pole, of the two second extending portions located on the same permanent magnetic pole is a22, and an included angle formed between the side walls, close to the center line of the alternating pole, of the two second air grooves located on both sides of the alternating pole is a2, wherein a22/a2 is 0.7-1.

Preferably, in a plane perpendicular to the central axis of the rotor core, an included angle formed between side walls, close to the central line of the magnetic poles, of the two second extending portions located on the same permanent magnet pole is a22, and an included angle formed by connecting lines of two end points of the radial outer edge of the permanent magnet and the center of the rotor core is am, where a22/am is 0.65-0.75.

Preferably, the radial thickness of the first extension part is t21, the radial thickness of the second extension part is t22, wherein t21/t22 is 0.4-0.6.

Preferably, in a plane perpendicular to the central axis of the rotor core, an included angle formed by connecting two end points of the radial outer edge of the first air slot and the center of the rotor core is a1, and an included angle formed between side walls, close to the center line of the magnetic pole, of two second extending portions located in the same permanent magnetic pole is a22, wherein a1/a22 is 0.1-0.15.

Preferably, the radial thickness of the first air groove is t1, the pole shoe thickness on the center line of the magnetic pole is ts1, wherein t1/ts1 is 0.4-0.6.

Preferably, the radial thickness of the second air groove is t2, and the radial thickness of the first extension part is t21, wherein t21/t2 is 0.2-0.4.

Preferably, the first air slot is symmetrical about the pole center line.

According to another aspect of the present application there is provided a consequent pole machine comprising a rotor assembly and a stator assembly, the rotor assembly being as described above.

The utility model provides a rotor assembly, including rotor core, rotor core includes the permanent magnetism pole and the alternative pole of arranging in turn along circumference, the permanent magnetism pole includes the mounting groove, install the permanent magnet in the mounting groove, the polarity of permanent magnet towards rotor core outer peripheral edges is same polarity, the both ends of mounting groove are provided with second air tank respectively, second air tank includes the groove body and follows first extension and the second extension that the groove body extends to the magnetic pole central line, first extension and second extension set gradually and form radial thickness degressive ladder groove. The rotor core of the rotor assembly is provided with the second air groove, the second air groove comprises a first extending portion and a second extending portion, the first extending portion and the second extending portion extend towards a magnetic pole center line, the first extending portion and the second extending portion form a step groove with unequal thickness, the thickness of the extending portion at the position close to the magnetic pole center line is thinner, the counter electromotive force is close to the position of a peak value, partial wave troughs can be lifted, partial wave crests are reduced, the counter electromotive force waveform acting side is more symmetrical, even harmonic content is reduced, the problem of torque pulsation increase caused by counter electromotive force harmonics of the alternating-pole motor is effectively solved, the counter electromotive force harmonic content is obviously reduced, the counter electromotive force harmonic distortion rate is reduced, and the motor performance is improved.

Drawings

FIG. 1 is a schematic structural view of a rotor assembly according to an embodiment of the present application;

FIG. 2 is a dimensional block diagram of a rotor assembly according to an embodiment of the present application;

FIG. 3 is a graph comparing back emf waveforms of a rotor assembly of an embodiment of the present application with a prior art rotor assembly;

FIG. 4 is a counter potential harmonic decomposition comparison of a rotor assembly of an embodiment of the present application and a prior art rotor assembly;

FIG. 5 is a magnetic flux distribution plot near the constant thickness extension of the rotor assembly;

FIG. 6 is a magnetic flux distribution plot near the stepped extension of the rotor assembly of an embodiment of the present application;

FIG. 7 is a comparison of counter potential waveforms for different forms of extensions;

FIG. 8 is a comparison graph of back emf harmonics for different forms of extensions;

FIG. 9 is a graph of back emf harmonic content as a function of a22/a21 for a rotor assembly of an embodiment of the present application;

FIG. 10 is a graph of back emf harmonic content as a function of t22/t21 for a rotor assembly of an embodiment of the present application;

FIG. 11 is a graph of back emf harmonic content, electromagnetic torque, as a function of a1/a22 for a rotor assembly of an embodiment of the present application.

The reference numerals are represented as:

1. a rotor core; 2. mounting grooves; 3. a permanent magnet; 4. a first air tank; 5. a second air tank; 6. a first extension portion; 7. a second extension portion; 8. a stator assembly.

Detailed Description

With combined reference to fig. 1 to 11, according to an embodiment of the present application, the rotor assembly includes a rotor core 1, the rotor core 1 includes permanent magnet poles and alternating poles alternately arranged along a circumferential direction, the permanent magnet poles include a mounting groove 2, a permanent magnet 3 is installed in the mounting groove 2, the polarity of the permanent magnet 3 facing the outer periphery of the rotor core 1 is the same polarity, the two ends of the mounting groove 2 are respectively provided with a second air groove 5, the second air groove 5 includes a groove body and a first extending portion 6 and a second extending portion 7 extending from the groove body to a magnetic pole center line, and the first extending portion 6 and the second extending portion 7 are sequentially arranged to form a stepped groove with a gradually decreasing radial thickness.

The rotor core 1 of the rotor assembly is provided with the second air slot 5, the second air slot 5 comprises a first extending portion 6 and a second extending portion 7 which extend towards a magnetic pole center line, the first extending portion 6 and the second extending portion 7 form stepped slots with unequal thicknesses, the thicknesses of the extending portions at positions close to the magnetic pole center line are thinner, a part of wave troughs can be lifted at positions where counter electromotive force is close to peak values, part of wave crests are reduced, the action sides of counter electromotive force waveforms are more symmetrical, even-number harmonic content is reduced, the problem of torque pulsation increase caused by counter electromotive force harmonics of an alternating-pole motor is effectively solved, counter electromotive force harmonic content is remarkably reduced, counter electromotive force harmonic distortion is reduced, and motor performance is improved.

Preferably, the two second air slots 5 are symmetrical about the center line of the magnetic pole, the extending parts of the second air slots 5 extend towards the center line of the magnetic pole, the air gap flux densities on the alternating poles and the permanent magnet poles are adjusted, the adjacent air gap flux densities are more symmetrical, and the torque fluctuation is reduced.

The extension part of the scheme of the application is thinner at the position close to the central line of the magnetic pole, the magnetic force lines of the extension part and the magnetic pole are distributed as shown by dotted lines in fig. 5 and 6, 4 magnetic force lines penetrate through the extension part of the scheme of the application, compared with a structure that the extension part penetrates through 3 magnetic force lines in the prior art, one more magnetic force line passes through the position close to the central line of the magnetic pole, and 1/4 more magnetic force lines pass through the extension part, which is shown in fig. 7 on the waveform of the back electromotive force, partial wave troughs in the prior art are lifted up at the position where the back electromotive force is close to the peak value, partial wave crests are reduced, so that the left side and the right side of the back electromotive force waveform are more symmetrical, and the even harmonic content is reduced, as shown.

Preferably, the first extension portion 6 and the second extension portion 7 are arranged on one side of the slot body close to the outer circle of the rotor core 1, so that the magnetic force lines can be more effectively adjusted.

The magnetic pole center line is provided with a first air slot 4, and the distance between the second air slot 5 and the outer periphery of the rotor core 1 is smaller than the distance between the first air slot 4 and the outer periphery of the rotor core 1.

The first air slot 4 can avoid the magnetic force lines at the center of the magnetic pole from being too concentrated, weaken a larger magnetic flux density peak value, enable the magnetic flux density waveform of an air gap of the adjacent magnetic pole to be more symmetrical, and enable the sine degree of the magnetic flux density waveform to be better, as shown in fig. 3, greatly weaken even-order counter electromotive force harmonics caused by asymmetry of the magnetic pole in the counter electromotive force harmonics, as shown in fig. 4, and further reduce torque pulsation compared with the prior art.

The included angle formed by the side walls, close to the center line of the magnetic pole, of the two first extension portions 6 located in the same permanent magnetic pole is a21, and the included angle formed by the side walls, close to the center line of the magnetic pole, of the two second extension portions 7 located in the same permanent magnetic pole is a22, wherein a22/a21 is 0.7-0.9. In the present embodiment, the plane of the side walls of the two first extension portions 6 close to the pole center line passes through the center axis of the rotor core 1, that is, the center axis of the rotor core 1 is located in the plane.

The smaller the ratio of the two is, the longer the extension part with the smaller thickness is, the weaker the limiting effect on the magnetic force lines at the center part of the magnetic pole is, the magnetic force lines cannot gather under the permanent magnet pole, on the contrary, the larger the ratio of the two is, the shorter the extension part with the smaller thickness is, the extension part gradually evolves into the extension part with the same thickness, as shown in fig. 8, the content of counter potential even-order harmonics increases. Research shows that the content of counter potential harmonic is small when a22/a21 is 0.7-0.9, as shown in fig. 9.

An included angle formed between the side walls, close to the center line of the magnetic pole, of the two second extending portions 7 located on the same permanent magnetic pole is a22, and an included angle formed between the side walls, close to the center line of the alternating pole, of the two second air grooves 5 located on the two sides of the alternating pole is a2, wherein a22/a2 is 0.7-1. In the present embodiment, the plane of the side walls of the two second extensions 7 passes through the central axis of the rotor core 1. When the plane where the side walls of the two second extending portions 7 are located does not pass through the central axis of the rotor core 1, the two second extending portions 7 need to satisfy the condition that, in the plane perpendicular to the central axis of the rotor core 1, an included angle between an end point of the radial outer edge of the two second extending portions 7, which is close to the magnetic pole center line, and a connecting line of the center of the rotor core 1 is a 22. Preferably, the planes of the side walls of the two second air slots 5 also pass through the central axis of the rotor core 1.

The ratio represents the pole-arc ratio of adjacent magnetic poles, the smaller the ratio, the larger the magnetic density amplitude under the permanent magnetic pole, the smaller the magnetic density of the alternate pole, and the asymmetry of the magnetic density, otherwise, the larger the ratio, the wider the pole shoe under the permanent magnetic pole, the smaller the constraint effect on the magnetic force line, the smaller the magnetic density, the larger the magnetic density under the alternate pole, and the asymmetry of the magnetic density is also increased. The study shows that the symmetry of the magnetic density of 0.7-1 is the best when the a22/a2 is equal to the magnetic density of the magnetic material.

In a plane perpendicular to the central axis of the rotor core 1, an included angle formed between the side walls, close to the central line of the magnetic pole, of the two second extending portions 7 located on the same permanent magnet pole is a22, an included angle formed by a connecting line between two end points of the radial outer edge of the permanent magnet 3 and the center of the rotor core 1 is am, wherein a22/am is 0.65-0.75. The ratio of the two is too large, effective magnetic density cannot be formed under the permanent magnet pole, the ratio of the two is too small, the extension part blocks magnetic lines excessively, and the utilization rate of the permanent magnet 3 is low, and researches show that the effect is the best when a22/am is 0.6-0.8.

The radial thickness of the first extension part 6 is t21, the radial thickness of the second extension part 7 is t22, wherein t21/t22 is 0.4-0.6. The ratio characterizes the ratio of the thicknesses of the extensions. If the ratio is too small, the second extension portion 7 cannot effectively block the magnetic lines of force, so that the waveform of the air gap flux density cannot be adjusted, and the first extension portion 6 excessively blocks the magnetic lines of force. Conversely, if the ratio is too large, the second extension portion 7 blocks the magnetic lines of force too much, so that the utilization rate of the permanent magnet is reduced, and more magnetic lines of force pass through the first extension portion 6, thereby forming a larger magnetic leakage. The study shows that the effect is best when t22/t21 is 0.4-0.6, as shown in figure 10.

In a plane perpendicular to the central axis of the rotor core 1, an included angle formed by connecting two end points of the radial outer edge of the first air slot 4 and the center of the rotor core 1 is a1, and an included angle formed between side walls, close to the center line of the magnetic pole, of two second extending portions 7 located on the same permanent magnetic pole is a22, wherein a1/a22 is 0.1-0.15. The ratio characterizes the proportion of the pole shoe occupied by the first air slot 4. The larger the ratio, the stronger the effective magnetic resistance formed by the first air groove 4, the stronger the modulating effect on the magnetic force lines, but the larger the ratio, the more the electromagnetic torque is reduced. Conversely, the smaller the ratio, the first air slot 4 is not enough to form an effective magnetic resistance, thereby adjusting the magnetic lines of force and reducing the counter-potential harmonic distortion rate. The research shows that the ratio has the best effect when being 0.1-0.15. As shown in fig. 11.

The radial thickness of the first air groove 4 is t1, the pole shoe thickness on the magnetic pole center line is ts1, wherein t1/ts1 is 0.4-0.6. The ratio represents the radial space of the pole shoe occupied by the first air groove 4, the larger the ratio is, the stronger the blocking effect on the magnetic force lines is, the larger the ratio is, the larger the blocking effect on the magnetic force lines is, the smaller the ratio is, the first air groove 4 cannot effectively modulate the magnetic force lines, and researches show that the effect is the best in the range of t1/ts1 being 0.4-0.6.

The radial thickness of the second air groove 5 is t2, the radial thickness of the first extension part 6 is t21, wherein t21/t2 is 0.2-0.4. Because the distribution of the magnetic lines of force of the alternating poles and the permanent magnets is inconsistent, the magnetic lines of force on the alternating poles are more easily affected by the armature reaction, and therefore, the two sides of the second air slot 5 need to be provided with different thickness modulation magnetic lines of force. The study shows that the modulation effect on the magnetic force lines is best when t21/t2 is 0.2-0.4.

Preferably, the first air slot 4 is symmetrical about the center line of the magnetic pole, which can further ensure the distribution uniformity of magnetic lines of force on both sides of the first air slot 4, and make the magnetic density of the whole air gap more sinusoidal.

The permanent magnet 3 is, for example, a linear type.

The rotor core 1 is laminated by soft magnetic material sheets, so that the rotor core 1 with alternating poles is magnetized to have another polarity under the influence of the permanent magnetic poles.

According to an embodiment of the present application, the alternating pole machine comprises a rotor assembly, which is the rotor assembly described above, and a stator assembly 8.

According to the alternating-pole motor designed by the technical scheme, the back electromotive force harmonic exploded view is shown in fig. 4, and compared with the prior art, the alternating-pole motor has smaller harmonic content.

It is readily understood by a person skilled in the art that the advantageous ways described above can be freely combined, superimposed without conflict.

The present invention is not intended to be limited to the particular embodiments shown and described, but is to be accorded the widest scope consistent with the principles and novel features herein disclosed. The foregoing is only a preferred embodiment of the present application, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present application, and these modifications and variations should also be considered as the protection scope of the present application.

Claims (12)

1. The utility model provides a rotor subassembly, its characterized in that, includes rotor core (1), rotor core (1) includes the permanent magnetism pole and the alternative pole of arranging in turn along circumference, the permanent magnetism pole includes mounting groove (2), install permanent magnet (3) in mounting groove (2), permanent magnet (3) are same polarity towards the polarity of rotor core (1) outer peripheral edges, the both ends of mounting groove (2) are provided with second air groove (5) respectively, second air groove (5) include the groove body and follow first extension (6) and second extension (7) that the groove body extends to the magnetic pole central line, first extension (6) with second extension (7) set gradually and form radial thickness degressive ladder groove.

2. The rotor assembly according to claim 1, characterized in that the first extension (6) and the second extension (7) are arranged at a side of the slot body close to the outer circle of the rotor core (1).

3. The rotor assembly according to claim 1, wherein a first air slot (4) is provided on the pole centerline, and a distance between the second air slot (5) and an outer circumference of the rotor core (1) is smaller than a distance between the first air slot (4) and the outer circumference of the rotor core (1).

4. The rotor assembly according to claim 1, wherein the included angle formed by the side walls of the two first extending portions (6) located in the same permanent magnet pole close to the center line of the magnetic pole is a21, and the included angle formed by the side walls of the two second extending portions (7) located in the same permanent magnet pole close to the center line of the magnetic pole is a22, wherein a22/a21 is 0.7-0.9.

5. The rotor assembly according to claim 1, wherein the included angle formed between the side walls of the two second extending portions (7) located at the same permanent magnet pole close to the center line of the magnetic pole is a22, and the included angle formed between the side walls of the two second air grooves (5) located at both sides of the alternating pole close to the center line of the alternating pole is a2, wherein a22/a2 is 0.7-1.

6. The rotor assembly according to claim 1, wherein in a plane perpendicular to the central axis of the rotor core (1), an included angle formed between side walls of two second extending portions (7) of the same permanent magnet pole close to the central line of the magnetic pole is a22, an included angle formed between two end points of the radial outer edge of the permanent magnet (3) and a connecting line of the center of the rotor core (1) is am, wherein a22/am is 0.65-0.75.

7. The rotor assembly according to claim 1, wherein the first extension (6) has a radial thickness t21 and the second extension (7) has a radial thickness t22, wherein t21/t22 is 0.4-0.6.

8. The rotor assembly according to claim 3, wherein in a plane perpendicular to the central axis of the rotor core (1), an included angle formed by connecting two end points of the radial outer edge of the first air slot (4) with the center of the rotor core (1) is a1, and an included angle formed by side walls, close to the center line of the magnetic pole, of two second extending portions (7) located at the same permanent magnetic pole is a22, wherein a1/a22 is 0.1-0.15.

9. The rotor assembly of claim 3, wherein the radial thickness of the first air slot (4) is t1, and the pole piece thickness on the pole centerline is ts1, where t1/ts1 is 0.4-0.6.

10. The rotor assembly according to claim 1, wherein the radial thickness of the second air slot (5) is t2, and the radial thickness of the first extension (6) is t21, wherein t21/t2 is 0.2-0.4.

11. A rotor assembly according to claim 3, wherein the first air slot (4) is symmetrical about a pole centre line.

12. A consequent pole machine comprising a stator assembly (8) and a rotor assembly, characterized in that the rotor assembly is according to any one of claims 1 to 11.

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