A motor

Abstract

The present invention relates to a motor, and in particular to a motor. The motor comprises a rotor and a stator that cooperate with each other, and the rotor comprises: a rotor support; a NdFeB permanent magnet, which is circumferentially distributed on the rotor support; a ferrite magnet, which covers the axial side of the NdFeB permanent magnet close to the stator; and a pole shoe, which is arranged on the rotor support and separates two adjacent NdFeB permanent magnets. The ferrite magnet is arranged on the axial side of the NdFeB permanent magnet, so that the NdFeB permanent magnet is far away from the stator core, and the air gap magnetic field at the location of the NdFeB permanent magnet is relatively uniform, thereby reducing the generation of eddy currents; in addition, the position close to the motor stator core is replaced by a ferrite magnet, which has good insulation and almost no eddy current loss even in a high-frequency rotating magnetic field. The technical problems that the rotor of the disc motor in the prior art is prone to generate eddy currents in the magnetic field, resulting in rotor demagnetization, and the salient pole rate is low are solved.

Description

Technical Field

[0001] The invention relates to a motor, and in particular to a motor. Background Art

[0002] In the existing permanent magnet magnetic disc motor, the rotor structure of the magnet in the magnetic circuit is mostly a surface mount structure. Figure 1-2 As shown, the rotor 1' and the stator 2' cooperate, the rotor 1' includes a rotor bracket 11' and a permanent magnet 12', the stator 2' includes a stator core 21', and the stator core 21' has a stator slot 211' on the end surface facing the permanent magnet 12', and the permanent magnet 12' is directly exposed in the air gap. This structure can bring advantages such as high torque coefficient and back electromotive force coefficient, but it also has many defects: such as large cogging effect, large torque pulsation, poor low-speed stability, etc.

[0003] like Figure 2 As shown, due to the setting of the stator slot 211', the air gap magnetic field at the position where the permanent magnet 12' is located is uneven, which is specifically reflected in: the closer to the notch position of the stator slot 211', the weaker the magnetic field is, the closer to the surface of the stator core 21', the higher the unevenness of the magnetic field is, and the center of the air gap is relatively uniform. The material used for the permanent magnet has good electrical conductivity, which will cause the eddy current loss of the permanent magnet to increase seriously, causing the temperature of the permanent magnet to rise sharply and demagnetize. When the motor needs to run at high speed and high power density, especially the structure with double stators or multiple stators that clamp the rotor between two stators, the demagnetization phenomenon is more obvious, which may cause the motor to fail to operate normally. In addition, due to the rotor structure, the disc motor cannot realize the IPM (internal permanent magnet) rotor structure of the traditional motor. Currently, most of them are SPM (surface mounted permanent magnet) structures, which makes the d-axis and q-axis inductances of the motor almost equal (Ld=Lq), and cannot realize weak magnetic speed control. However, many current motor usage scenarios, especially motors used in the electric vehicle industry, generally require the motor to have a certain weak magnetic capability, which the disc motor cannot do. Summary of the invention

[0004] In order to solve the technical problems in the prior art that the rotor of the disc motor is prone to generate eddy currents in the magnetic field, resulting in rotor demagnetization and low salient pole rate, the present invention proposes a motor to solve the above technical problems. The technical solution of the present invention is as follows:

[0005] A motor includes a rotor and a stator that cooperate with each other, wherein the rotor includes: a rotor support; NdFeB permanent magnets, which are circumferentially distributed on the rotor support; ferrite magnets, which cover the axial side of the NdFeB permanent magnets close to the stator; and pole shoes, which are arranged on the rotor support and separate two adjacent NdFeB permanent magnets.

[0006] By arranging ferrite magnets on the axial side of the NdFeB permanent magnets, on the one hand, the NdFeB permanent magnets are kept away from the stator core, and the air gap magnetic field at the location of the NdFeB permanent magnets is relatively uniform, thereby reducing the generation of eddy currents; on the other hand, the position close to the stator core of the motor is replaced by ferrite magnets, which have good insulation properties and almost no eddy current losses even in a high-frequency rotating magnetic field; in addition, ferrite magnets have magnetism and can compensate for the loss of air gap magnetic field strength caused by the increase in the air gap.

[0007] Pole shoes are set on the rotor bracket to separate two adjacent NdFeB permanent magnets, which greatly reduces the q-axis magnetic flux linkage reluctance of the motor, thereby increasing the q-axis inductance, that is, Lq increases and the salient pole rate increases. In addition, the increase in air gap will reduce the d-axis inductance and increase the salient pole rate, which can improve the dynamic weak magnetic performance of the motor.

[0008] Furthermore, the NdFeB permanent magnets are circumferentially distributed on the same axial side of the rotor support, and the ferrite magnets cover the axial side of the NdFeB permanent magnets away from the rotor support.

[0009] Furthermore, there is one stator, and the stator is located on the axially outer side of the rotor close to the ferrite magnet.

[0010] Furthermore, the rotor bracket is provided with mounting holes distributed in the circumferential direction, the NdFeB permanent magnets are embedded in the mounting holes, and both axial sides of the NdFeB permanent magnets are covered with the ferrite magnets.

[0011] Furthermore, the NdFeB permanent magnet cooperates with the ferrite magnets on both sides to fill the mounting hole.

[0012] Furthermore, there are two stators, and the two stators are respectively located on two axial sides of the rotor.

[0013] Furthermore, the pole shoe is made of a high magnetic permeability soft magnetic material, and the pole shoe passes through the rotor bracket.

[0014] Furthermore, the stator comprises a stator core, a stator slot is formed on one end of the stator core facing the ferrite magnet, and a stator winding is arranged on the stator core.

[0015] Based on the above technical solution, the technical effects that can be achieved by the present invention are:

[0016] 1. The motor of the present invention arranges a ferrite magnet on the axial side of the NdFeB permanent magnet. On the one hand, the NdFeB permanent magnet is kept away from the stator core, and the air gap magnetic field at the location of the NdFeB permanent magnet is relatively uniform, thereby reducing the generation of eddy currents. On the other hand, the position close to the motor stator core is replaced by a ferrite magnet. The ferrite magnet has good insulation and almost no eddy current loss is generated even in a high-frequency rotating magnetic field. In addition, the ferrite magnet has magnetism and can compensate for the loss of air gap magnetic field strength caused by the increase of the air gap.

[0017] 2. The motor of the present invention can be provided with a NdFeB permanent magnet and a ferrite magnet on an axial side surface of the rotor bracket, and the formed rotor can be matched with a stator; the NdFeB permanent magnet can also be embedded in the rotor bracket, and the ferrite magnets are covered on both circumferential sides of the NdFeB permanent magnet, and the formed rotor can be axially sandwiched between two stators and matched with the two stators; a pole shoe is further provided to separate two adjacent NdFeB permanent magnets, and the pole shoe structure can greatly reduce the q-axis magnetic flux linkage magnetic resistance of the motor, thereby increasing the q-axis inductance Lq and realizing the salient pole effect; combined with the increase of the air gap, the d-axis inductance Ld is reduced, the salient pole ratio p=Lq / Ld, and the salient pole ratio is increased, which can improve the dynamic weak magnetic performance of the motor;

[0018] 3. In the motor of the present invention, the air gap length between the stator and the rotor is increased, which can reduce the generation of eddy currents, and the air gap magnetic field at the location of the NdFeB permanent magnet is uniform and has low power loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the structure of the rotor and the single stator of the motor in the prior art;

[0020] Figure 2 It is a schematic diagram of the structure of the rotor and double stators of a motor in the prior art;

[0021] Figure 3 It is a structural schematic diagram of a motor according to Embodiment 1 of the present invention;

[0022] Figure 4 is a schematic structural diagram of a rotor of Embodiment 1;

[0023] Figure 5 for Figure 4 AA cross-section diagram;

[0024] Figure 6 It is a schematic diagram of the magnetic field distribution when the rotor and stator of the motor cooperate;

[0025] Figure 7 for Figure 4 BB cross-section diagram;

[0026] Figure 8It is a schematic diagram of the motor's rotor and stator when they are matched;

[0027] Fig. 9 is a schematic structural diagram of a rotor according to a second embodiment of the present invention;

[0028] Fig.10 for Fig. 9 CC cross-section diagram;

[0029] Fig.11 for Fig. 9 DD cross-section diagram;

[0030] Fig.12 It is a schematic diagram of the rotor and stator of the motor of the second embodiment when they are matched;

[0031] Among them: 1-rotor; 11-rotor bracket; 111-mounting hole; 112-center axis hole; 12-NdFeB permanent magnet; 13-ferrite magnet; 14-pole shoe; 2-stator; 21-stator core; 211-stator slot; 22-stator winding; 3-casing; 4-end cover; 5-rotating shaft; 6-fan; 7-cover plate; 1'-rotor; 11'-rotor bracket; 12'-permanent magnet; 2'-stator; 21'-stator core; 211'-stator slot. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0034] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0035] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0036] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0037] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0038] Embodiment 1

[0039] like Figure 3-8 As shown, this embodiment provides a motor, specifically a disc motor, including a rotor 1 and a stator 2, two stators 2, and the rotor 1 is axially sandwiched between the two stators 2. Specifically, the motor includes a housing 3 and an end cover 4, the housing 3 and the end cover 4 are fixedly connected to form a cavity with an accommodating space, the rotor 1 and the stator 2 are both placed in the cavity, the two stators 2 are respectively fixedly arranged on the inner wall of the housing 3 and the inner wall of the end cover 4, the rotor 1 is rotatably arranged between the two stators 2, the rotor 1 is rotatably arranged through a rotating shaft 5, and the two ends of the rotating shaft 5 are respectively rotatably arranged on the housing 3 and the end cover 4 through bearings.

[0040] The rotor 1 includes a rotor support 11, a NdFeB permanent magnet 12 and a ferrite magnet 13. The NdFeB permanent magnet 12 is arranged on the rotor support 11, and the ferrite magnet 13 covers at least one axial side of the NdFeB permanent magnet 12. The rotor support 11 is circular, and a central axis hole 112 is opened at the center of the rotor support 11 to facilitate connection with the rotating shaft 5. The rotor support 11 is provided with mounting holes 111 along the circumferential direction to mount the NdFeB permanent magnet 12. Specifically, there are a plurality of mounting holes 111, which are evenly distributed along the circumference of the rotor support 11, and the mounting holes 111 are through holes.

[0041] The NdFeB permanent magnet 12 is disposed in the mounting hole 111. Specifically, the NdFeB permanent magnet 12 is embedded in the mounting hole 111, and the axial sides of the NdFeB permanent magnet 12 do not protrude from the mounting hole 111. Preferably, the NdFeB permanent magnet 12 is fan-shaped or trapezoidal. Both axial sides of the NdFeB permanent magnet 12 are covered with ferrite magnets 13. The shape of the ferrite magnet 13 is adapted to the shape of the NdFeB permanent magnet 12. The two ferrite magnets 13 and the NdFeB permanent magnet 12 in between form a stacked structure, and the entire stacked structure fills the mounting hole 111 together. Figure 6 As shown, the structure of the rotor 1 of this embodiment makes the NdFeB permanent magnet 12 away from the stator 2, and the air gap magnetic field at the position of the NdFeB permanent magnet 12 is more uniform than that of the prior art, thereby reducing the generation of eddy currents; in addition, the position close to the motor stator core is replaced by a ferrite magnet, which has good insulation properties and almost no eddy current loss even in a high-frequency rotating magnetic field; the ferrite magnet has magnetism and can compensate for the loss of air gap magnetic field strength caused by the increase of the air gap.

[0042] The rotor 1 also includes a pole shoe 14 disposed on the rotor bracket 11, and the pole shoe 14 separates two adjacent NdFeB permanent magnets 12. Specifically, a receiving hole is opened between two adjacent mounting holes 111 of the rotor bracket 11, and the pole shoe 14 is placed in the receiving hole. Preferably, the receiving hole is a through hole that penetrates the rotor bracket 11, and the receiving hole is adapted to the shape of the pole shoe 14. The pole shoe 14 just fills the receiving hole, and multiple pole shoes 14 and NdFeB permanent magnets 12 are located on the same circumference. Preferably, the pole shoe 14 is made of a high magnetic permeability soft magnetic material. By arranging the pole shoe 14 between the adjacent NdFeB permanent magnets of the motor rotor, the q-axis magnetic flux linkage magnetic resistance of the motor is greatly reduced, thereby increasing the q-axis inductance Lq and realizing the salient pole effect. The arrangement of the pole shoe 14 increases Lq, and the increase of the air gap δ reduces the inductance Ld of the d-axis, and the salient pole ratio p=Lq / Ld, so the salient pole ratio is greatly increased.

[0043] Through simulation, it can be seen that the rotor of this embodiment has a salient pole ratio p, and the d-axis inductance becomes smaller and smaller as the air gap increases, but the q-axis inductance hardly changes, thereby increasing the salient pole ratio, and the effect is better when used in a hybrid permanent magnet disc motor rotor. Through the ANSYS simulation results, after adding pole shoes, the salient pole ratio of an ordinary disc motor rotor can be expanded to 2-3 times, but for a hybrid rotor structure, the salient pole ratio can be expanded to 5-6 times.

[0044] The stator 2 includes a stator core 21 and a stator winding 22. A stator slot 211 is formed on the end surface of the stator core 21 close to the rotor 1. The slot opening of the stator slot 211 faces the rotor 1. The stator winding 22 is arranged on the stator core 21. Figure 6 As shown, the rotor 1 cooperates with the stator 2 on both sides. Since ferrite magnets 13 are arranged on both sides of the NdFeB permanent magnet 12 of the rotor 1, the NdFeB permanent magnet 12 is farther away from the stator core 21 than in the prior art, and the air gap length δ from the NdFeB permanent magnet 12 to the stator core 21 is increased. The magnetic field at the position where the NdFeB permanent magnet 12 is located is more uniform than that in the prior art, reducing the generation of eddy currents. The position close to the stator core of the motor is replaced by a ferrite magnet. Since ferrite has very good insulation properties, almost no eddy current loss is generated even in a high-frequency rotating magnetic field.

[0045] Preferably, the outer end surface of the end cover 4 is formed with a receiving cavity, and the rotating shaft 5 extends into the receiving cavity to connect the fan 6, that is, the rotating shaft 5 drives the fan 6 to rotate to dissipate heat for the motor. More preferably, the outer fixed cover of the receiving cavity is provided with a cover plate 7 to protect the fan 6.

[0046] Based on the above structure, the motor of this embodiment has the following advantages in actual use:

[0047] (1) The rotor temperature is greatly reduced: In the prior art, the motor runs at a speed of 2000RPM and outputs 20KW for one hour, and the rotor temperature reaches 180 degrees. The motor runs at a speed of 3200RPM and outputs 20KW for 12 minutes, and the rotor temperature reaches 220 degrees. After that, the rotor is permanently demagnetized. In the motor of this embodiment, the motor runs at a speed of 2000RPM and outputs 20KW for one hour, and the rotor temperature reaches 90 degrees. The motor runs at a speed of 3200RPM and outputs 20KW for one hour, and the rotor temperature reaches 100 degrees. There is no demagnetization of the rotor.

[0048] (2) Cost reduction: Due to the significant drop in rotor temperature, the NdFeB material used in the permanent magnet can be reduced from the original UH to SH or even H, which will greatly reduce the cost of NdFeB materials. Although the ferrite material is increased, the cost of ferrite materials is negligible compared to the UH NdFeB material. Based on the current purchase price, the price of UH NdFeB and ferrite of the same size is about 25 times that of each other, and the overall structure saves costs.

[0049] (3) The cogging effect is greatly reduced: the motor cogging torque is reduced from the original 3.5NM to 0.5NM, and the low-speed stability is also greatly improved.

[0050] (4) Efficiency is greatly improved.

[0051] Embodiment 2

[0052] like Figure 9-12 As shown, this embodiment is basically the same as the first embodiment, and the only difference is that, in the rotor 1 of this embodiment, the rotor bracket 11 has only one axial side surface with the NdFeB permanent magnet 12, and the axial side surface of the NdFeB permanent magnet 12 away from the rotor bracket 11 is covered with a ferrite magnet 13. Specifically, there is no need to set the mounting hole 111 and the receiving hole on the rotor bracket 11, and the NdFeB permanent magnet 12 can be attached to one axial side surface of the rotor bracket 11 and distributed circumferentially. The pole shoe 14 is attached to the same axial side surface of the rotor bracket 11, and the pole shoe 14 is located between two adjacent NdFeB permanent magnets 12.

[0053] The motor of this embodiment comprises a rotor 1 and a stator 2, and the stator 2 is arranged on a side of the rotor 1 close to the ferrite magnet 13. By arranging the ferrite magnet 13, the air gap length δ from the NdFeB permanent magnet 12 to the stator core 21 is increased, which can make the magnetic field uniform and reduce eddy currents.

[0054] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A motor, comprising a rotor (1) and a stator (2) that cooperate with each other, characterized in that: The rotor (1) comprises: Rotor support (11); Neodymium iron boron permanent magnets (12), the neodymium iron boron permanent magnets (12) being distributed circumferentially on the rotor support (11); A ferrite magnet (13), wherein the ferrite magnet (13) covers the axial side surface of the NdFeB permanent magnet (12) close to the stator (2); A pole shoe (14), wherein the pole shoe (14) is arranged on the rotor support (11), and the pole shoe (14) separates two adjacent NdFeB permanent magnets (12).

2. A motor according to claim 1, characterized in that: The NdFeB permanent magnets (12) are circumferentially distributed on the same axial side of the rotor support (11), and the ferrite magnets (13) cover the axial side of the NdFeB permanent magnets (12) away from the rotor support (11).

3. A motor according to claim 2, characterized in that: There is one stator (2), and the stator (2) is located on the axially outer side of the rotor (1) close to the ferrite magnet (13).

4. The motor according to claim 1, characterized in that: The rotor bracket (11) is provided with mounting holes (111) distributed in the circumferential direction, the NdFeB permanent magnet (12) is embedded in the mounting hole (111), and both axial sides of the NdFeB permanent magnet (12) are covered with the ferrite magnet (13).

5. A motor according to claim 4, characterized in that: The NdFeB permanent magnet (12) cooperates with the ferrite magnets (13) on both sides to fill the mounting hole (111).

6. The motor according to claim 4, characterized in that: The pole shoe (14) is made of a high-magnetic-permeability soft magnetic material, and the pole shoe (14) passes through the rotor bracket (11).

7. The motor according to claim 4, characterized in that: There are two stators (2), and the two stators (2) are respectively located on two axial sides of the rotor (1).

8. A motor according to any one of claims 1 to 7, characterized in that: The stator (2) comprises a stator core (21), a stator slot (211) is formed on one end of the stator core (21) facing the ferrite magnet (13), and a stator winding (22) is arranged on the stator core (21).

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