Permanent magnet magnetism-assisting synchronous reluctance motor rotor and motor

Abstract

The invention discloses a rotor and a motor of a permanent magnet magnetic-assisted synchronous reluctance motor, and belongs to the field of permanent magnet magnetic-assisted synchronous reluctance motors, each magnetic pole in a rotor iron core comprises multiple layers of magnetic barriers which are sequentially arranged from inside to outside, and each layer of magnetic barrier is in bilateral symmetry in an axial tangent plane; the minimum distance between the tail end of the magnetic barrier and the outer circle of the rotor is sequentially reduced from the innermost magnetic barrier to the outermost magnetic barrier, and the thickness of the magnetic barrier is sequentially reduced from the innermost magnetic barrier to the outermost magnetic barrier. Each magnetic barrier is filled with cured ferrite plastic magnets; and the whole rotor is magnetized. On the basis, the rotor iron core is formed by axially laminating a plurality of silicon steel sheets, and the adjacent silicon steel sheets are staggered by a preset angle, so that the whole rotor iron core is skewed by a certain angle. According to the invention, the step heights of the air gap flux densities generated by the rotor magnetic field are different, and the sinusoidal property of air gap harmonic waves is effectively improved, so that the content of the air gap harmonic waves is reduced, and vibration and noise during high-speed operation of the motor are reduced.

Description

Technical Field

[0001] The present invention belongs to the field of permanent magnet assisted synchronous reluctance motors, and more specifically, relates to permanent magnet assisted synchronous reluctance motor rotors and motors. Background Art

[0002] The BLDC (brushless DC motor) used in traditional washing machines is a rotor tangentially excited internal permanent magnet synchronous motor (SPOKE) topology, which has the characteristics of high power density and high torque density. However, this rotor SPOKE topology motor has disadvantages such as large vibration noise and low efficiency at high speed, which makes it difficult to meet the requirements of washing machines for low motor vibration noise and high efficiency under dehydration conditions.

[0003] The permanent magnet assisted synchronous reluctance motor combines the characteristics of the permanent magnet synchronous motor and the synchronous reluctance motor. This motor makes full use of the reluctance torque and permanent magnet torque. It has the advantages of high power density, high efficiency, wide speed regulation range and low vibration and noise. It can be well adapted to various working conditions of washing machines and has a wide range of application scenarios.

[0004] However, in the existing permanent magnet assisted synchronous reluctance motor, the air gap harmonic content is still relatively high. When the motor runs at high speed, the air gap harmonics will still cause relatively large vibration and noise. Summary of the invention

[0005] In view of the defects of the prior art and the need for improvement, the present invention provides a permanent magnet assisted synchronous reluctance motor rotor and a motor, the purpose of which is to reduce the air gap harmonic content in the permanent magnet assisted synchronous reluctance motor, thereby reducing the vibration and noise generated when the motor runs at high speed.

[0006] To achieve the above object, according to one aspect of the present invention, a permanent magnet assisted synchronous reluctance motor rotor is provided, wherein each magnetic pole in the rotor core comprises: a plurality of magnetic barriers arranged sequentially from the inside to the outside, each layer of magnetic barriers being bilaterally symmetrical in an axial section; the minimum distance between the end of the magnetic barrier and the outer circle of the rotor decreases from the innermost magnetic barrier to the outermost magnetic barrier, and the thickness of the magnetic barrier decreases from the innermost magnetic barrier to the outermost magnetic barrier;

[0007] Each magnetic barrier is filled with solidified ferrite plastic magnets;

[0008] The rotor is magnetized as a whole.

[0009] Furthermore, the rotor core is formed by axially stacking a plurality of silicon steel sheets, and adjacent silicon steel sheets are staggered by a preset angle, so that the rotor core is twisted at a certain angle as a whole.

[0010] Furthermore, the outermost magnetic barrier is a type I magnetic barrier, and each layer of magnetic barriers within the outermost magnetic barrier is a U-shaped magnetic barrier.

[0011] Furthermore, in each layer of magnetic barriers within the outermost magnetic barrier, the corners of each layer of magnetic barriers are configured to be arc-shaped.

[0012] Furthermore, in each layer of magnetic barriers within the outermost layer of magnetic barriers, arcs at inner and outer corners on the same side of the same layer of magnetic barriers are parallel to each other.

[0013] Furthermore, in each layer of magnetic barriers, a middle magnetic bridge is provided in the middle of the magnetic barriers that meet the preset stress condition; the preset stress condition is: when the middle magnetic bridge is not provided, the stress of the magnetic bridge at the end of the magnetic barrier is greater than or equal to a preset threshold value;

[0014] Furthermore, the middle magnetic bridge is provided to satisfy the condition that the stress of the magnetic bridge at the end of the magnetic barrier is less than a preset threshold.

[0015] In some optional embodiments, the number of magnetic barrier layers set in each magnetic pole is 3, and the minimum distance l1 between the end of the innermost magnetic barrier and the outer circle of the rotor, the minimum distance l2 between the end of the middle magnetic barrier and the outer circle of the rotor, and the minimum distance l3 between the end of the outermost magnetic barrier and the outer circle of the rotor satisfy: l1=1.28l2=1.8l3.

[0016] In some optional embodiments, the thickness τ3 of the innermost magnetic barrier, the thickness τ2 of the middle magnetic barrier, and the thickness τ1 of the outermost magnetic barrier satisfy: τ3=1.13τ2=1.8τ1.

[0017] According to another aspect of the present invention, a permanent magnet assisted synchronous reluctance motor is provided, comprising: any one of the permanent magnet assisted synchronous reluctance motor rotors provided by the present invention.

[0018] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

[0019] (1) In the permanent magnet assisted synchronous reluctance motor rotor provided by the present invention, multiple layers of magnetic barriers are arranged in sequence from the inside to the outside in each magnetic pole. Since the magnetic barriers are filled with solidified ferrite plastic magnets, the overall strength of the rotor is relatively large, and the magnetic bridge at the end of the magnetic barrier can be made narrower while ensuring the strength of the rotor; the minimum distance between the end of the magnetic barrier and the outer circle of the rotor decreases from the innermost magnetic barrier to the outermost magnetic barrier, and the thickness of the magnetic barrier decreases from the innermost magnetic barrier to the outermost magnetic barrier, thereby making the step heights of the air gap magnetic density generated by the rotor magnetic field different, effectively improving the sinusoidality of the air gap harmonics, thereby reducing the air gap harmonic content and reducing the vibration and noise of the motor when running at high speed.

[0020] (2) In the preferred embodiment of the permanent magnet assisted synchronous reluctance motor rotor provided by the present invention, adjacent silicon steel sheets are staggered by a preset angle among the silicon steel sheets stacked to form the motor rotor, so that the rotor core is twisted by a certain angle as a whole, thereby further improving the sinusoidal nature of the air gap harmonics, thereby further reducing the vibration and noise of the motor when running at high speed.

[0021] (3) In the preferred embodiment of the permanent magnet assisted synchronous reluctance motor rotor provided by the present invention, the multiple layers of magnetic barriers in the same magnetic pole are hybrid magnetic barriers, wherein the outermost magnetic barrier is a type I magnetic barrier, and each layer of magnetic barrier within the outermost magnetic barrier is a U-type magnetic barrier, thereby increasing the area of ​​ferrite plastic magnetism while ensuring the strength requirements.

[0022] (4) In the preferred embodiment of the permanent magnet assisted synchronous reluctance motor rotor provided by the present invention, the corners of the U-shaped magnetic barrier are set to be arc-shaped, so that the ferrite plastic magnet filled in the magnetic barrier can be fully magnetized. In a further preferred embodiment, the arcs at the inner and outer corners on the same side of the same layer of magnetic barriers are parallel to each other, so that the direction of the armature reaction magnetic field can be along the direction of these arcs, which is beneficial to improve the reluctance torque of the motor.

[0023] (5) In the preferred embodiment of the permanent magnet assisted synchronous reluctance motor rotor provided by the present invention, a middle magnetic bridge is provided in the middle of the magnetic barrier with large end magnetic bridge stress, thereby ensuring the strength of the rotor structure.

[0024] (6) For the permanent magnet assisted synchronous reluctance motor rotor provided by the present invention, when the number of magnetic barrier layers is 3, the minimum distance l1 between the end of the innermost magnetic barrier and the outer circle of the rotor, the minimum distance l2 between the end of the middle magnetic barrier and the outer circle of the rotor, and the minimum distance l3 between the end of the outermost magnetic barrier and the outer circle of the rotor are set to satisfy: l1=1.28l2=1.8l3. Simulation results show that this minimum distance setting can maximize the sinusoidality of the air gap harmonics. In a further preferred embodiment, the thickness τ3 of the innermost magnetic barrier, the thickness τ2 of the middle magnetic barrier, and the thickness τ1 of the outermost magnetic barrier are further set to satisfy: τ3=1.13τ2=1.8τ1, thereby further improving the sinusoidality of the air gap harmonics and achieving the purpose of minimizing the air gap harmonic content. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A front view of a permanent magnet assisted synchronous reluctance motor rotor provided by an embodiment of the present invention;

[0026] Figure 2 A schematic diagram of magnetic barrier parameters in a permanent magnet assisted synchronous reluctance motor rotor provided in an embodiment of the present invention;

[0027] Figure 3 A schematic diagram of the three-dimensional structure of the rotor core in the permanent magnet assisted synchronous reluctance motor rotor provided by an embodiment of the present invention;

[0028] Figure 4 A schematic diagram of the three-dimensional structure of a permanent magnet assisted synchronous reluctance motor rotor provided in an embodiment of the present invention;

[0029] Figure 5 Schematic diagram of the comparison of air gap flux density between the embodiment of the present invention and the conventional permanent magnet assisted synchronous reluctance motor;

[0030] Figure 6 Schematic diagram comparing the air gap flux density harmonic distribution of the embodiment of the present invention and the conventional permanent magnet assisted synchronous reluctance motor;

[0031] In all drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0032] 1-inner magnetic barrier, 2-middle magnetic barrier, 3-outer magnetic barrier, 4-rotor core, 5-inner magnetic bridge, 6-middle magnetic bridge, 7-outer magnetic bridge, 8-corner of inner magnetic barrier, 9-corner of middle magnetic barrier, 10-inner magnetic steel, 11-middle magnetic steel, 12-outer magnetic steel. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0034] In the present invention, the terms "first", "second", etc. (if any) in the present invention and the accompanying drawings are used to distinguish similar objects but not necessarily to describe a specific order or sequence.

[0035] In order to effectively reduce the vibration and noise of a permanent magnet assisted synchronous reluctance motor under high-speed operation, the present invention provides a permanent magnet assisted synchronous reluctance motor rotor and a motor, the overall concept of which is to optimize the structure of the motor to improve the sinusoidal nature of the air gap magnetic flux, thereby reducing the harmonic content of the air gap magnetic flux and reducing the vibration and noise generated by the air gap magnetic flux.

[0036] Based on the above concept, in the permanent magnet assisted synchronous reluctance motor rotor provided by the present invention, each magnetic pole of the rotor core contains multiple layers of magnetic barriers arranged in sequence from the inside to the outside, and the present invention specifically optimizes the design of the structure and parameters related to the magnetic barriers. The present invention finds that when the minimum distance between the end of the magnetic barrier and the outer circle of the rotor decreases from the innermost magnetic barrier to the outermost magnetic barrier, and the thickness of the magnetic barrier decreases from the innermost magnetic barrier to the outermost magnetic barrier, the step height of the air gap magnetic flux generated by the rotor magnetic field is different, and the sinusoidality of the air gap harmonics will be enhanced. In the present invention, the optimization design of the structure and parameters related to the magnetic barrier is proposed based on this discovery. On this basis, in order to increase the magnetic barrier design space without affecting the rotor strength, the present invention uses ferrite plastic magnets to fill the magnetic barrier space, ensuring the overall strength of the rotor, so that the magnetic bridge at the end of the magnetic barrier can be made narrower according to the need to improve the sinusoidality of the air gap harmonics.

[0037] In the present invention, the number of magnetic barrier layers can be set to different numbers as needed. Without loss of generality, in the following embodiments, three layers of magnetic barriers are used as an example for description.

[0038] The following are examples.

[0039] Embodiment 1:

[0040] A permanent magnet assisted synchronous reluctance motor rotor. Optionally, in this embodiment, the number of poles of the motor rotor is 4.

[0041] like Figure 1 to Figure 4 As shown, in this embodiment, each magnetic pole in the rotor core 4 includes: three layers of magnetic barriers arranged in sequence from the inside to the outside, which are sequentially recorded as inner magnetic barrier 1, middle magnetic barrier 2 and outer magnetic barrier 3, and each layer of magnetic barrier is bilaterally symmetrical in the axial section; the magnetic bridges at the ends of the three layers of magnetic barriers are sequentially recorded as inner magnetic bridge 5, middle magnetic bridge 6 and outer magnetic bridge 7;

[0042] like Figure 2 As shown, in this embodiment, the minimum distance l1 between the end of the inner magnetic barrier and the outer circle of the rotor, the minimum distance l2 between the end of the middle magnetic barrier and the outer circle of the rotor, and the minimum distance l3 between the end of the outermost magnetic barrier and the outer circle of the rotor are reduced in sequence, and specifically meet the following conditions: l1=1.28l2=1.8l3;

[0043] The thickness τ3 of the inner magnetic barrier, the thickness τ2 of the middle magnetic barrier and the thickness τ1 of the outer magnetic barrier decrease in sequence, and specifically satisfy: τ3=1.13τ2=1.8τ1;

[0044] Each magnetic barrier is filled with solidified ferrite plastic magnets;

[0045] The rotor is magnetized as a whole.

[0046] In this embodiment, on the basis of filling the magnetic barriers with ferrite plastic magnets to ensure the strength of the rotor, the shortest distance between the end of each layer of magnetic barriers and the outer circle of the rotor and the relationship between the thickness of each layer of magnetic barriers are set as above, which can make the air gap magnetic density generated by the permanent magnet more sinusoidal and reduce the harmonic content of the air gap, which will greatly reduce the vibration noise of the motor.

[0047] It is easy to understand that the above relationship between the shortest distance between the end of each layer of magnetic barrier and the outer circle of the rotor and the thickness of each layer of magnetic barrier is only a preferred embodiment of the present invention and should not be understood as the only limitation of the present invention. In addition, when the number of magnetic barrier layers changes, the specific quantitative relationship between the shortest distance between the end of each layer of magnetic barrier and the outer circle of the rotor and the thickness of each layer of magnetic barrier should be specifically set according to the corresponding number of layers, and can be determined by simulation in actual applications.

[0048] In order to further improve the sinusoidality of the air gap harmonics, such as Figure 3 and Figure 4 As shown, in this embodiment, the rotor core is formed by axially stacking a plurality of silicon steel sheets, and the adjacent silicon steel sheets are staggered by a preset angle, so that the rotor core is twisted by a certain angle as a whole. Since the magnetic barrier is filled with ferrite plastic magnets in this embodiment, the setting of staggering the silicon steel sheets by a preset angle can ensure that the ferrite plastic magnets fill the magnetic barrier. Finally, after the filled ferrite plastic magnets are solidified, the permanent magnet poles formed are also twisted by the same angle as the rotor, thereby achieving the effect of magnetic pole tilting, thereby further improving the sinusoidality of the air gap magnetic density.

[0049] like Figure 1 to Figure 4 As shown, in this embodiment, the outer magnetic barrier 3 is a type I magnetic barrier, and the middle magnetic barrier 2 and the inner magnetic barrier 1 are both U-type magnetic barriers, realizing a hybrid magnetic barrier structure, thereby increasing the area of ​​ferrite plastic magnetism while ensuring strength requirements.

[0050] like Figure 2 As shown, in this embodiment, the corners 8 of the inner layer magnetic barrier and the corners 9 of the middle layer magnetic barrier are both set to be arc-shaped, so that the ferrite plastic magnet filled in the magnetic barrier can be fully magnetized. On this basis, the arcs at the inner and outer corners on the same side of the same layer of magnetic barrier are parallel to each other, so that the direction of the armature reaction magnetic field can be along the direction of these arcs, so that the salient pole ratio of the motor is increased, thereby improving the reluctance torque of the motor, and at high speeds, it can improve the efficiency of the motor.

[0051] like Figure 1 to Figure 4 As shown, in this embodiment, middle magnetic barriers are respectively arranged in the middle of the inner magnetic barrier and the middle magnetic barrier, and the widths of the two middle magnetic barriers are equal, thereby ensuring the strength of the rotor structure.

[0052] In practical applications, the magnetic barriers that need to be set up with a middle magnetic bridge can be determined by simulation. Specifically, the rotor strength can be determined by stress simulation. If the stress of the magnetic bridge at the end of a layer of magnetic barriers is too large (greater than or equal to a preset threshold), a middle magnetic bridge needs to be set up in the middle of the magnetic barrier. It is easy to understand that the set middle magnetic bridge should meet the following requirements: after the magnetic bridge is set up, the stress of the magnetic bridge at the end of the magnetic barrier is less than a preset threshold. The preset threshold can be set accordingly according to the actual stress intensity requirements.

[0053] The permanent magnet assisted synchronous reluctance motor provided in the present embodiment can manufacture corresponding silicon steel sheets after determining the magnetic barrier structure and related parameters; after stacking a plurality of silicon steel sheets along the axial direction according to the axial length, adjacent silicon steel sheets are staggered by a preset angle, so that the rotor is twisted by a certain angle as a whole and the silicon steel sheets are fixed; then, ferrite plastic magnets are injection molded into the magnetic barrier by injection molding until the ferrite plastic magnets fill the magnetic barrier area; after the ferrite plastic magnets are solidified, the rotor is magnetized as a whole to make the ferrite plastic magnets magnetic, at this time, the solidified ferrite plastic magnets in the inner magnetic barrier, the middle magnetic barrier and the outer magnetic barrier respectively form the inner magnetic steel 10, the middle magnetic steel 11 and the outer magnetic steel 12, as shown in FIG. Figure 4 In general, the permanent magnet assisted synchronous reluctance motor provided in this embodiment can, on the one hand, make the air gap flux density generated by the permanent magnet more sinusoidal and reduce the air gap harmonic content, which will greatly reduce the vibration noise of the motor; on the other hand, it can increase the salient pole ratio of the motor, thereby improving the reluctance torque of the motor, and at high speed, it can improve the efficiency of the motor.

[0054] Embodiment 2:

[0055] A permanent magnet assisted synchronous reluctance motor comprises: the permanent magnet assisted synchronous reluctance motor rotor provided in the above-mentioned embodiment 1.

[0056] Based on the permanent magnet assisted synchronous reluctance motor rotor proposed in the above-mentioned embodiment 1, the permanent magnet assisted synchronous reluctance motor provided in this embodiment will have its vibration and noise reduced when running at high speed.

[0057] Figure 5 The figure shows a schematic diagram comparing the air gap flux density of the rotor of this embodiment and the conventional permanent magnet assisted synchronous reluctance motor. Figure 5 It can be seen from the results that, compared with the traditional permanent magnet assisted synchronous reluctance motor, in this embodiment, the overall waveform of the rotor air gap magnetic flux is closer to a sine wave, that is, in this embodiment, the rotor air gap magnetic flux is more sinusoidal, and accordingly, the air gap harmonic content will be effectively reduced.

[0058] Figure 6 The figure shows a schematic diagram comparing the air gap flux density harmonic distribution of the rotor of the present embodiment and the conventional permanent magnet assisted synchronous reluctance motor. Figure 6It can be seen from the results that, compared with the traditional permanent magnet assisted synchronous reluctance motor, in this embodiment, the air gap flux density amplitude corresponding to each harmonic amplitude is reduced, that is, in this embodiment, the harmonic content is less, and therefore, this embodiment will have less vibration and noise.

[0059] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A permanent magnet assisted synchronous reluctance motor rotor, characterized in that: Each magnetic pole in the rotor core includes: multiple layers of magnetic barriers arranged from the inside to the outside, each layer of magnetic barriers is bilaterally symmetrical in the axial section; the minimum distance between the end of the magnetic barrier and the outer circle of the rotor decreases from the innermost magnetic barrier to the outermost magnetic barrier, and the thickness of the magnetic barrier decreases from the innermost magnetic barrier to the outermost magnetic barrier; Each magnetic barrier is filled with solidified ferrite plastic magnets; The rotor is magnetized as a whole.

2. The permanent magnet assisted synchronous reluctance motor rotor according to claim 1, characterized in that: The rotor core is formed by stacking a plurality of silicon steel sheets in the axial direction, and adjacent silicon steel sheets are staggered at a preset angle, so that the rotor core is twisted at a certain angle as a whole.

3. The permanent magnet assisted synchronous reluctance motor rotor according to claim 1 or 2, characterized in that: The outermost magnetic barrier is a type I magnetic barrier, and each layer of magnetic barriers within the outermost magnetic barrier is a U-shaped magnetic barrier.

4. The permanent magnet assisted synchronous reluctance motor rotor as claimed in claim 3, characterized in that: In each layer of magnetic barriers within the outermost magnetic barrier, the corners of each layer of magnetic barriers are arranged in an arc shape.

5. The permanent magnet assisted synchronous reluctance motor rotor as claimed in claim 4, characterized in that: In each layer of magnetic barriers within the outermost layer of magnetic barriers, arcs at inner and outer corners on the same side of the same layer of magnetic barriers are parallel to each other.

6. The permanent magnet assisted synchronous reluctance motor rotor according to claim 3, characterized in that: In each layer of magnetic barriers, a middle magnetic bridge is provided in the middle of the magnetic barriers that meet the preset stress condition; the preset stress condition is: when the middle magnetic bridge is not provided, the stress of the magnetic bridge at the end of the magnetic barrier is greater than or equal to a preset threshold value; Furthermore, the provided middle magnetic bridge satisfies that: the stress of the magnetic bridge at the end of the magnetic barrier is less than the preset threshold.

7. The permanent magnet assisted synchronous reluctance motor rotor according to claim 1 or 2, characterized in that: The number of magnetic barrier layers set in each magnetic pole is 3, and the minimum distance l1 from the end of the innermost magnetic barrier to the outer circle of the rotor, the minimum distance l2 from the end of the middle magnetic barrier to the outer circle of the rotor, and the minimum distance l3 from the end of the outermost magnetic barrier to the outer circle of the rotor satisfy: l1=1.28l2=1.8l3.

8. The permanent magnet assisted synchronous reluctance motor rotor according to claim 7, characterized in that: The thickness τ3 of the innermost magnetic barrier, the thickness τ2 of the middle magnetic barrier, and the thickness τ1 of the outermost magnetic barrier satisfy: τ3=1.13τ2=1.8τ1.

9. A permanent magnet assisted synchronous reluctance motor, characterized in that: include: A permanent magnet assisted synchronous reluctance motor rotor as claimed in any one of claims 1 to 8.

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