CN220775609U - Permanent magnet DC motor - Google Patents

Abstract

The present disclosure relates to a permanent magnet direct current motor including a rotor shaft, a plurality of rotors directly or indirectly fixed to the rotor shaft, and a plurality of stators arranged around the plurality of rotors. Each rotor is provided with a plurality of permanent magnets around a central axis of the rotor shaft, the plurality of permanent magnets including S-pole permanent magnets and N-pole permanent magnets alternately arranged. Each stator is provided with a plurality of windings about a central axis, the plurality of windings including a U-phase winding, a V-phase winding, and a W-phase winding, the plurality of windings being arranged in a fixed order about the central axis. The permanent magnet direct current motor comprises at least a first rotor and a second rotor, the first rotor and the second rotor are arranged with permanent magnets of the same polarity in a direction around the central axis differing from each other by an angle α greater than or equal to zero, and the permanent magnet direct current motor comprises at least a first stator and a second stator, the in-phase windings of which are arranged with respect to each other in a direction around the central axis by an angle β greater than or equal to zero. Wherein angle β is not equal to angle α.

Description

Permanent Magnet DC Motor

Technical Field

The present disclosure relates to a permanent magnet direct current motor.

Background technique

Cogging torque is a periodic torque that objectively exists in existing permanent magnet motors. The reason for its generation is that in permanent magnet motors, the slotted structure of the stator causes the magnetic resistance of the magnetic circuit corresponding to each pole of the motor to be unbalanced, causing the rotor to tend to be pulled to some fixed positions where the magnetic resistance path is the smallest.

Cogging torque can cause torque pulsation in permanent magnet motors, which in turn leads to speed fluctuations. Torque pulsation can also cause vibration and noise in the motor, and seriously affect the positioning accuracy and servo performance of the motor, especially at low speeds. In addition, cogging torque can make it difficult to start the motor.

To weaken the influence of cogging torque, the most common approach is to set rotor skew poles or stator skew slots, but this method has a high process complexity.

It would be desirable to solve the above problems in a simple structural and cost-effective manner.

Utility Model Content

In response to the problems and needs mentioned above, the present disclosure proposes a vertically stacked multi-stator and multi-rotor permanent magnet DC brushless motor, which adopts stator conduction misalignment and/or rotor polarity misalignment to weaken the influence of cogging torque, reduce output torque fluctuation, and reduce motor vibration and noise.

The permanent magnet DC motor proposed in the present disclosure includes a rotor shaft, a plurality of rotors fixed directly or indirectly to the rotor shaft, and a plurality of stators arranged around the plurality of rotors. Each rotor is provided with a plurality of permanent magnets arranged around the central axis of the rotor shaft, and the plurality of permanent magnets include S-pole permanent magnets and N-pole permanent magnets arranged alternately. Each stator is provided with a plurality of windings arranged around the central axis, and the plurality of windings include U-phase windings, V-phase windings and W-phase windings, and the plurality of windings are arranged in a fixed order around the central axis. Wherein, the permanent magnet DC motor includes at least a first rotor and a second rotor, and the first rotor and the second rotor are arranged in a direction around the central axis so that permanent magnets of the same polarity differ from each other by an angle α greater than or equal to zero, and the permanent magnet DC motor includes at least a first stator and a second stator, and the in-phase windings of the first stator and the second stator are arranged in a direction around the central axis so that they differ from each other by an angle β greater than or equal to zero, wherein the angle β is not equal to the angle α.

Preferably, the first rotor and the second rotor have a pole pair number P, and the angle α satisfies: 90°/P≤α≤270°/P.

Preferably, the angle α satisfies: 150°/P≤α≤210°/P.

Preferably, the angle α=180/P.

Preferably, the pole pair number P is 4 or 5.

Preferably, each rotor has the same number and size of permanent magnets.

Preferably, the total number of windings of the first stator and the second stator is R, and the angle β satisfies: 180/R≤β≤540/R.

Preferably, the angle β satisfies: 345/R≤β≤345/R.

Preferably, the angle β=360/R.

Preferably, the total number of windings R is 12.

Preferably, each stator has the same total number of windings.

The best embodiments for implementing the present disclosure will be described in more detail below with reference to the accompanying drawings so that the features and advantages of the present disclosure can be easily understood.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings of the embodiments of the present disclosure are briefly introduced below. The drawings are only used to show some embodiments of the present disclosure, but not to limit all embodiments of the present disclosure thereto.

FIG1 shows a partial front view of a motor according to a first exemplary embodiment;

FIG2 shows an exploded view of a motor according to a first exemplary embodiment;

FIG3 shows a partial front view of a motor according to a first exemplary embodiment;

FIG. 4 shows an end view of a first stator according to a first exemplary embodiment;

FIG5 shows an end view of a second stator according to a first exemplary embodiment, the viewing direction being the same as FIG4 ;

FIG6 shows a partial exploded view of a motor according to a second exemplary embodiment;

FIG7 shows a partial exploded view of a motor according to a third exemplary embodiment;

FIG8 shows a partial exploded view of a motor according to a fourth exemplary embodiment;

FIG9 shows a partial exploded view of a motor according to a fifth exemplary embodiment;

Reference numerals list

100 Rotor shaft

10 First rotor

20 First stator

21 Winding

30 Second rotor

40 Second stator

41 Winding

50 Third rotor

60 Third stator

61 Winding

70 Fourth rotor

80 Fourth stator

81 Winding

Detailed ways

In order to make the purpose, technical solution and advantages of the technical solution of the present disclosure clearer, the technical solution of the embodiment of the present disclosure will be clearly and completely described in conjunction with the drawings of the specific embodiments of the present disclosure. The same figure marks in the drawings represent the same parts. It should be noted that the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present disclosure.

Compared to the embodiments shown in the drawings, feasible embodiments within the scope of the present disclosure may have fewer components, other components not shown in the drawings, different components, differently arranged components, or differently connected components, etc. In addition, two or more components in the drawings may be implemented in a single component, or a single component shown in the drawings may be implemented as multiple separate components.

Unless otherwise defined, the technical terms or scientific terms used herein shall have the usual meanings understood by persons with ordinary skills in the field to which the present disclosure belongs. The words "first", "second" and similar words used in the patent application specification and claims of the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "one" do not necessarily indicate a quantity restriction. Words such as "include" or "comprise" mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly. In addition, "multiple" in the present disclosure means two or more.

In general, the present disclosure provides a permanent magnet DC motor, which includes a rotor shaft, a plurality of rotors directly or indirectly fixed to the rotor shaft, and a plurality of stators arranged around the plurality of rotors. The rotor shaft has a central axis A, which can also serve as the central axis of each rotor and each stator. The number of rotors and stators is preferably equal, and each rotor is accommodated in a stator, so that the rotor and the stator form a drive unit. When the permanent magnet DC motor is running, the plurality of rotors rotate due to the interaction with the plurality of stators, and drive the common rotor shaft to rotate.

In the present disclosure, the number of drive units may be two or more. Preferably, the number of drive units of the permanent magnet DC motor is 2, 3 or 4. Specifically, in the first embodiment shown in FIGS. 1-5 , the second embodiment shown in FIG. 6 , and the third embodiment shown in FIG. 7 , the number of drive units is 2. In the fourth embodiment shown in FIG. 8 , the number of drive units is 3. In the fifth embodiment shown in FIG. 9 , the number of drive units is 4.

The following first introduces the overall principle of the present disclosure in conjunction with the above embodiments.

The present disclosure generally proposes a vertically stacked multi-stator multi-rotor permanent magnet DC brushless motor, which uses stator conduction misalignment and/or rotor polarity misalignment to reduce the influence of cogging torque.

For the rotor disclosed in the present invention, each rotor is provided with a plurality of permanent magnets arranged around the central axis A, wherein the plurality of permanent magnets include a plurality of permanent magnets having different magnetizing directions and arranged alternately with polarities, and for simplicity, these two types of permanent magnets are respectively referred to as S-pole permanent magnets and N-pole permanent magnets. These permanent magnets are arranged alternately, that is, each S-pole permanent magnet is adjacent to two N-pole permanent magnets, and each N-pole permanent magnet is adjacent to two S-pole permanent magnets. For details, see Figures 2 and 4-9. Preferably, the plurality of permanent magnets can be configured in a ring shape, and each permanent magnet preferably has the same size.

Preferably, the permanent magnet disclosed in the present invention is a plastic magnet permanent magnet. During the production process, magnetic orientation is performed in the injection molding stage to determine the N pole and S pole of the plastic magnet permanent magnet.

Preferably, the multiple rotors of the permanent magnet DC motor have permanent magnets of the same number and size.

The pole pair number P of the rotors shown in the drawings of the present disclosure is 4, that is, there are 4 S-pole permanent magnets and 4 N-pole permanent magnets, but the scope of the present disclosure is not limited thereto. For example, a rotor with a pole pair number of 2, 3, 5, 6, 7, etc. may also be used. However, preferably, the pole pair number P of the permanent magnet is set to 4 or 5.

Each stator is provided with a plurality of windings arranged around the central axis A, the plurality of windings including a U-phase winding, a V-phase winding and a W-phase winding connected to the U-phase terminal, the V-phase terminal and the W-phase terminal, respectively. In the drawings, the U-phase winding, the V-phase winding and the W-phase winding are represented by letters U, V and W, respectively.

The motor of the present disclosure can be connected to 220V or 380V AC. The permanent magnet DC motor has its own driver to convert AC into DC. The three-phase winding of the motor is star-connected, and the U, V, W phase terminals and the U, V, W phase windings are defined by the on-off control of the control program in different orders.

For each stator, after power is turned on, the multiple windings are arranged in a fixed order around the central axis. The fixed order can be the order of "U phase winding-V phase winding-W phase winding-U phase winding-V phase winding...", or it can be the order of "U phase winding-W phase winding-V phase winding-U phase winding-W phase winding...". Wherein, if the electrical connection is not considered, the multiple stators can have windings with exactly the same structure and the same arrangement. However, in the present disclosure, for the sake of convenience, even in the absence of current, the windings connected to the electrical terminals of the corresponding phases will be named according to the names of the corresponding phases, that is, as mentioned above, the windings connected to the U phase terminal, the V phase terminal and the W phase terminal are respectively called the U phase winding, the V phase winding and the W phase winding.

In a direction around the central axis A, the plurality of windings are alternately arranged in the order of a U-phase winding, a V-phase winding, and a W-phase winding.

In the preferred embodiment shown in the drawings of the present disclosure, the number of windings of each stator is 12, including 4 U-phase windings, 4 V-phase windings and 4 W-phase windings, but the scope of the present disclosure is not limited thereto. Other suitable numbers of windings are also possible.

In order to reduce the influence of the cogging torque, the present disclosure proposes a multi-rotor, multi-stator staggered arrangement scheme. First, the permanent magnets of the same polarity of at least two rotors (referred to as the first rotor and the second rotor) among the multiple rotors of the permanent magnet DC motor are arranged to differ from each other by an angle α greater than or equal to zero in the direction around the central axis. In other words, the permanent magnets of the same polarity of the first rotor and the second rotor are arranged in a positive position/aligned arrangement, or are arranged at an angle α offset from each other. Secondly, at least two stators (referred to as the first stator and the second stator) among the multiple stators are arranged in a direction around the central axis so that the same-phase windings differ from each other by an angle β greater than or equal to zero. In other words, the same-phase windings of the first stator and the second stator (windings of the same phase after power-on) are arranged in a positive position/aligned arrangement, or are arranged at an angle α offset from each other. At the same time, the angle β is also made not equal to the angle α.

By means of the above-mentioned staggered arrangement, especially the staggered arrangement of both the rotor and the stator, the influence of the cogging torque can be effectively weakened. At the same time, by making the angle β not equal to the angle α, the weakening effects of the cogging torque caused by the rotor misalignment and the stator misalignment are prevented from canceling each other out.

In addition, each rotor and stator used in the present invention is an independent component before assembly. For each rotor, the N pole and S pole are determined when the rotor is formed. During assembly, the misalignment of the magnetic poles can be achieved by adjusting the positions between different rotors. In this way, in addition to the simple manufacturing process of the rotor itself, it also has the advantage of flexible installation, because during installation, the misalignment can be achieved by adjusting the positions of the relevant rotors, and the misalignment angle can be changed by changing the relative positions of the rotors. For the stator, each stator may not have a misaligned arrangement in structure, but the misalignment effect is produced by program control of the on and off of the UVW phases of the two stators, for example, the U and V phases of one stator are connected and the W phase is disconnected, while the V and W phases of the other stator are connected and the U phase is disconnected. In this way, the stator misalignment angle can be flexibly adjusted by controlling the power supply.

According to a preferred embodiment of the present disclosure, for two rotors that are misaligned with each other, if the two rotors have the same number of pole pairs P, the angle α between the two rotors satisfies: 90°/P≤α≤270°/P, or 135°/P≤α≤225°/P, or 150°/P≤α≤210°/P, or 165°/P≤α≤195°. More preferably, the angle α=180/P, which can best achieve the purpose of reducing the influence of the cogging torque.

According to a preferred embodiment of the present disclosure, for two stators that are offset from each other, the offset angle β satisfies: 180/P≤β≤540/P, where P is the total number of windings. More preferably, the offset angle can satisfy 330/P≤β≤390/P, or 345/P≤β≤375/P. By setting such an offset angle, the purpose of reducing the influence of the cogging torque can be well achieved. Most preferably, the offset angle β of the offset arrangement is 360/P, which can best achieve the purpose of reducing the influence of the cogging torque.

Among them, in the preferred embodiments shown in the drawings of the present disclosure, the number of windings is 12, with 4 U-phase windings, 4 V-phase windings and 4 W-phase windings, but the scope of the present disclosure is not limited thereto. Other suitable numbers of windings may also be used. Preferably, each stator of the permanent magnet DC motor has the same total number of windings.

The following is a detailed introduction taking the first embodiment shown in FIGS. 1-5 as an example.

The permanent magnet DC motor comprises a first stator 20, a second stator 40, and a first rotor 10 and a second rotor 30 surrounded by the first stator 20 and the second stator 40, both of which are fixed to a rotor shaft 100. As shown in FIG1 , the first stator 20 has a plurality of windings 21, and the second stator 40 has a plurality of windings 41. Each stator is preferably a cylindrical structure with two ends open, and has a plurality of teeth extending from the inner wall of the stator, and the teeth may be provided with tooth slots for winding the winding.

In this embodiment, the S-pole permanent magnets of the two rotors are aligned with the S-pole permanent magnets, and the N-pole permanent magnets are aligned with the N-pole permanent magnets, that is, the two rotors are aligned with each other/arranged in the right position, which is clearly shown in Figure 2. The two stators are arranged in a staggered manner, specifically, the in-phase windings of the first stator and the second stator are arranged in the direction around the central axis at an angle β=360°/12=30° different from each other.

In the first embodiment, preferably as shown in FIG3 , the U-phase winding of the first stator 20 is aligned with the V-phase winding of the second stator 40, the V-phase winding of the first stator 20 is aligned with the W-phase winding of the second stator 40, and the W-phase winding of the first stator 20 is aligned with the U-phase winding of the second stator 40. In an embodiment not shown, the corresponding relationship of the stators can be arranged as follows: the U-phase winding of the first stator 20 is aligned with the W-phase winding of the second stator 40, the V-phase winding of the first stator 20 is aligned with the U-phase winding of the second stator 40, and the W-phase winding of the first stator 20 is aligned with the V-phase winding of the second stator 40.

Through this staggered arrangement, when the two rotors are affected by the cogging torque of the first stator 20, the rotor will not be affected by the cogging torque of the second stator 40, and when it is affected by the cogging torque of the second stator 40, it is not in a position affected by the first stator 20. In this way, the rotation speed of the rotor shaft can be stabilized and the overall impact of the cogging torque on the output can be reduced.

FIG6 shows a second embodiment of the present disclosure. Different from the first embodiment, in the second embodiment, the two stators are aligned/arranged in position with each other, while the two rotors are arranged in a staggered position with each other, and the first rotor 21 and the second rotor 22 are arranged so that, along the central axis, the S-pole permanent magnet of the first rotor 21 is aligned with the N-pole permanent magnet of the second rotor 22, and the N-pole permanent magnet of the first rotor 21 is aligned with the S-pole permanent magnet of the second rotor 22. In this arrangement, the two rotors are arranged in a direction around the central axis so that the permanent magnets of the same polarity differ from each other by an angle α=180°/4=45°.

Through this staggered arrangement, when the speed of the first rotor fluctuates due to the influence of the cogging torque of the two stators, the second rotor will not be affected by the cogging torque. When the second rotor rotates to a position affected by the cogging torque, the first rotor is not in a position affected by the cogging torque. In this way, the overall rotational speed of the rotor can be stabilized and the overall influence of the cogging torque on the rotor can be reduced.

FIG7 shows a third embodiment of the present disclosure. In this embodiment, the two stators are arranged in a staggered manner, and the two rotors are also arranged in a staggered manner. The angle α of the two rotors is 180/4=45°, and the angle β of the two stators is 360°/12=30°. In this embodiment, the corresponding relationship of the windings of the two stators is V-W, W-U, U-V. In an embodiment not shown, the corresponding relationship of the windings of the two stators is V-U, W-V, U-W.

FIG8 shows a fourth embodiment of the present disclosure. In this embodiment, the permanent magnet DC motor includes a first rotor 10, a second rotor 30, a third rotor 50 and a first stator 20, a second stator 40, and a third stator 60, and the three stators are respectively provided with a plurality of windings 21, 41, and 61. The three rotors are arranged in a positive position/aligned manner with each other, and in the three stators, two adjacent stators are arranged in a staggered manner. Specifically, the winding correspondence of the three stators is U-V-U, V-W-V, and W-U-W. In other embodiments not shown, the winding correspondence of the three stators can be U-V-W, V-W-U, W-U-V or U-W-V, V-U-W, W-V-U, etc. In addition, in an embodiment not shown, the three rotors can be arranged so that each adjacent two rotors are arranged in a staggered manner with each other.

FIG9 shows a fifth embodiment of the present disclosure, in which a permanent magnet DC motor comprises a first rotor 10, a second rotor 30, a third rotor 50, a fourth rotor 70 and a first stator 20, a second stator 40, a third stator 60, and a fourth stator 80. The four stators are respectively provided with a plurality of windings 21, 41, 61, and 81. The four rotors are arranged in a staggered manner, that is, the angle of difference between them is α=180/4=45°, and the four stators are also arranged in a staggered manner, and the angle of difference is β=360°/12=30°. Similarly, this embodiment is only an example of staggered arrangement. In an embodiment not shown, the four stators can be arranged in other staggered manners.

For an embodiment with three or more rotors, preferably, any two adjacent rotors among the rotors are arranged in a manner that satisfies the aforementioned angle α. Similarly, for an embodiment with three or more stators, preferably, any two adjacent stators among the stators are arranged in a manner that satisfies the aforementioned angle β. In this way, the reduction of the cogging torque can be achieved in a simple assembly manner.

In the description of the present disclosure, if each S-pole permanent magnet of one rotor is aligned with each S-pole permanent magnet of another rotor along the center axis direction, and each N-pole permanent magnet of the one rotor is aligned with each N-pole permanent magnet of the other rotor along the center axis direction, then the two rotors are called "positive" arrangement, or "aligned" arrangement. If the two rotors are not "positive" or "aligned", but one of the rotors is rotated about the center axis by an angle relative to the other rotor, then the two rotors are called "misaligned" arrangement, or one of the rotors is called "misaligned" arrangement relative to the other rotor. That is, the permanent magnets of the same polarity of the two rotors in the "misaligned" arrangement are not aligned, but differ from each other by a certain angle. In the present disclosure, a permanent magnet is "aligned" with another permanent magnet, which means that the line connecting the centers of the two permanent magnets is parallel to the center axis of the rotor. In other words, if the center planes of the two permanent magnets along the center axis of the rotor coincide, then the two permanent magnets are "aligned".

Similarly, if the windings of the corresponding phases of one stator are aligned with the windings of the corresponding phases of another stator along the central axis, the two stators are said to be arranged "in position". If the two stators are not arranged "in position", but one of the stators is rotated around the central axis by an angle relative to the other stator, the two stators are said to be arranged "off position", or one of the stators is said to be arranged "off position" relative to the other stator. That is, the windings of the corresponding phases of the two stators arranged "off position" are not aligned, but differ by a certain angle. In other words, the connecting line of the windings of the corresponding phases is not parallel to the central axis of the stator.

The exemplary implementation scheme of the present disclosure is described in detail above with reference to the preferred embodiments. However, it can be understood by those skilled in the art that, without departing from the concept of the present disclosure, various modifications and variations can be made to the above-mentioned specific embodiments, and various technical features and structures proposed in the present disclosure can be combined in various ways without exceeding the protection scope of the present disclosure, which is determined by the attached claims.

Claims (11)

1. A permanent magnet DC motor comprising a rotor shaft, a plurality of rotors directly or indirectly fixed to the rotor shaft, and a plurality of stators disposed around the plurality of rotors,

each rotor is provided with a plurality of permanent magnets arranged around a central axis of the rotor shaft, the plurality of permanent magnets including S-pole permanent magnets and N-pole permanent magnets alternately arranged;

each stator is provided with a plurality of windings arranged around the central axis, the plurality of windings comprising a U-phase winding, a V-phase winding, and a W-phase winding, the plurality of windings being arranged in a fixed order around the central axis;

wherein the permanent magnet direct current motor comprises at least a first rotor and a second rotor, which are arranged with permanent magnets of the same polarity in a direction around a central axis, differ from each other by an angle α of greater than or equal to zero, and the permanent magnet direct current motor comprises at least a first stator and a second stator, which are arranged with their in-phase windings in a direction around the central axis, differ from each other by an angle β of greater than or equal to zero, wherein the angle β is not equal to the angle α.

2. The permanent magnet direct current motor of claim 1 wherein,

the first rotor and the second rotor have a pole pair number P, and the angle α satisfies: alpha is more than or equal to 90 degrees/P and less than or equal to 270 degrees/P.

3. The permanent magnet direct current motor according to claim 2, wherein,

the angle α satisfies: alpha is more than or equal to 150 degrees/P and less than or equal to 210 degrees/P.

4. The permanent magnet direct current motor according to claim 3, wherein,

the angle α=180/P.

5. Permanent magnet direct current motor according to any of claims 2-4, characterized in that the pole pair number P is 4 or 5.

6. A permanent magnet direct current motor according to any of claims 2-4, characterized in that each rotor has the same number and size of permanent magnets.

7. The permanent magnet direct current motor of claim 1 wherein,

the total number of windings of the first stator and the second stator is R, and the angle β satisfies: beta is not less than 180/R and not more than 540/R.

8. The permanent magnet direct current motor of claim 7 wherein,

the angle beta satisfies: beta is more than or equal to 345/R and less than or equal to 345/R.

9. The permanent magnet direct current motor of claim 8, wherein the angle β = 360/R.

10. Permanent magnet direct current motor according to any of claims 7-9, characterized in that the total number of windings R is 12.

11. The permanent magnet direct current motor according to any one of claims 7 to 9, characterized in that,

each stator has the same total number of windings.