Surface-mounted rotor structure and motor

Abstract

The present invention provides a surface-mounted rotor structure and a motor. The rotor structure includes: a rotor body; a plurality of main permanent magnets are provided on the outer peripheral wall of the rotor body at uniform intervals, and auxiliary permanent magnets are provided at both circumferential edges of the main permanent magnets; the magnetization directions of the auxiliary permanent magnets are the same as that of the main permanent magnets; adjacent auxiliary permanent magnets are in contact with each other along the circumferential direction of the rotor body. In the surface-mounted rotor structure of the present invention, two auxiliary permanent magnets are placed on both sides of the main permanent magnet, which increases the magnetic flux density at the edge of the main permanent magnet, reduces the distortion rate of the back electromotive force of the motor winding, and at the same time plays a role in fixing the main permanent magnet. It can also effectively reduce the current under the rated torque of the motor, reduce the heat generation and vibration of the motor. Since the permanent magnets on the rotor are closely attached to each other, it not only strengthens the overall strength of the permanent magnets, avoids relative movement with the rotor, improves the positioning accuracy, but also reduces the assembly difficulty of the rotor permanent magnets.

Description

Technical Field

[0001] The present invention belongs to the technical field of motors, and particularly relates to a surface-mounted rotor structure and a motor. Background Art

[0002] Compared with ordinary motors, permanent magnet synchronous motors have smaller speed fluctuations, larger motor power density, and higher efficiency, and are generally applied to high-end precision fields such as machine tools and servo robots.

[0003] The traditional permanent magnet motor rotors can be divided into three types: built-in type, surface type, and claw pole type. Due to the relatively small inter-pole leakage flux of the surface-mounted permanent magnet rotor, its pole arc coefficient and cross-sectional shape can be arbitrarily adjusted according to the requirements of the spatial distribution of the air gap magnetic flux density, and its manufacturing process is relatively simple. Therefore, the rotors of many permanent magnet motors often adopt surface-mounted magnetic steel structures.

[0004] For a surface-mounted motor rotor, serious leakage flux will occur at the edge of the magnetic steel, thereby reducing the back electromotive force constant and the back electromotive force distortion rate of the motor. When the torque is constant, the smaller the back electromotive force constant, the more serious the motor heating. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is that serious leakage flux will occur at the edge of the magnetic steel of the existing surface-mounted motor rotor, and thus a surface-mounted rotor structure and a motor are provided.

[0006] To solve the above problems, the present invention provides a surface-mounted rotor structure, including:

[0007] A rotor body;

[0008] A plurality of main magnetic steels are provided on the outer peripheral wall of the rotor body at evenly spaced intervals, and auxiliary magnetic steels are provided at both circumferential edges of the main magnetic steels; the auxiliary magnetic steels have the same magnetization direction as the main magnetic steels;

[0009] Adjacent auxiliary magnetic steels are in contact with each other along the circumferential direction of the rotor body.

[0010] The object of the present invention and the technical problems to be solved can be further realized by adopting the following technical measures.

[0011] Preferably, the thickness of the main magnetic steel gradually decreases from the circumferential symmetry axis to both edges, and the thickness d1 of the auxiliary magnetic steel is equal to the edge thickness d2 of the main magnetic steel.

[0012] Preferably, the thickness d1 of the auxiliary magnetic steel and the edge thickness d2 of the main magnetic steel are less than or equal to 1.5 mm.

[0013] Preferably, the auxiliary magnetic steel is of a tile structure and is closely attached to the outer wall of the rotor body.

[0014] Preferably, all the auxiliary magnetic steels in the rotor structure have the same size.

[0015] Preferably, the main magnet is adhesively bonded to the outer peripheral wall of the rotor body, and / or, the auxiliary magnet is adhesively bonded to the outer peripheral wall of the rotor body.

[0016] Preferably, the rotor structure further includes a binding band that is wound around the surface of the main magnet.

[0017] Preferably, the auxiliary magnet and the main magnet are of an integral structure.

[0018] An electric motor employs the above-mentioned surface-mounted rotor structure.

[0019] The surface-mounted rotor structure and the electric motor provided by the present invention at least have the following beneficial effects:

[0020] In the surface-mounted rotor structure of the present invention, two auxiliary magnets are placed on both sides of the main magnet to prevent magnetic leakage at the edge of the main magnet, increase the magnetic flux density at the edge of the main magnet, reduce the distortion rate of the back electromotive force of the motor winding, and at the same time play a role in fixing the main magnet. It can also effectively reduce the current under the rated torque of the motor, reduce the heat generation and vibration of the motor. Since the rotor magnets are closely fitted, it not only strengthens the overall magnet strength, avoids relative movement with the rotor, improves the positioning accuracy, but also reduces the assembly difficulty of the rotor magnets. Description of the Drawings

[0021] Figure 1 is a schematic structural diagram of the surface-mounted rotor structure according to an embodiment of the present invention;

[0022] Figure 2 is an axial schematic diagram of the surface-mounted rotor structure according to an embodiment of the present invention;

[0023] Figure 3 is a partial schematic diagram of the main magnet and the auxiliary magnet according to an embodiment of the present invention;

[0024] Figure 4 is a schematic magnetic circuit diagram of a rotor structure in the prior art;

[0025] Figure 5 is an equivalent magnetic circuit diagram of a rotor structure in the prior art.

[0026] The reference numerals are represented as:

[0027] 1. Rotor body; 2. Main magnet; 3. Auxiliary magnet; 4. Binding band; 5. Stator structure. Detailed Embodiments

[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0029] Combined with Figures 1 to 3 As shown, an embodiment of the present invention provides a surface-mounted rotor structure, including: a rotor body 1; a plurality of main magnets 2 are provided on the outer peripheral wall of the rotor body 1 at evenly spaced intervals, and auxiliary magnets 3 are provided at both circumferential edges of the main magnets 2; the magnetization directions of the auxiliary magnets 3 and the main magnets 2 are the same; adjacent auxiliary magnets 3 are in contact with each other along the circumferential direction of the rotor body 1.

[0030] In the surface-mounted rotor structure provided in this embodiment, two auxiliary magnets 3 are placed on both sides of the main magnet 2 of the surface-mounted permanent magnet motor, preventing magnetic leakage at the edges of the main magnet 2, increasing the magnetic flux density at the edges of the main magnet 2, reducing the distortion rate of the line back electromotive force of the motor, and at the same time playing a role in fixing the main magnet 2. Compared with the rotor structure of a salient-pole motor with a similar structure in the prior art, the direct and quadrature axis inductances on the rotor are different. Due to the exposed iron core remaining between the magnetic poles, the magnetic field lines at the edges of the main magnet will enter the protruding part of the rotor iron core, resulting in a relatively large magnetic leakage coefficient of the rotor structure, a low utilization rate of the permanent magnet, and a large torque ripple, affecting the comprehensive performance of the motor. However, the rotor structure of this application is a cathode structure, there is no reluctance torque, the torque ripple is small, and the control of the motor will be simpler and more efficient.

[0031] Preferably, the thickness of the main magnet 2 gradually decreases from the circumferential symmetry axis to both edges, the thickness d1 of the auxiliary magnet 3 is equal to the edge thickness d2 of the main magnet 2, and further, the thickness d1 of the auxiliary magnet 3 and the edge thickness d2 of the main magnet 2 are less than or equal to 1.5 mm.

[0032] In the field of motors, the back electromotive force distortion rate is an important parameter for measuring the performance of permanent magnet synchronous motors, indicating the amount of harmonic content in the back electromotive force in the stator when the motor runs without load. The less the harmonic content, the lower the distortion rate of the line back electromotive force in the stator of the motor. During the operation of the motor, the fluctuations of the motor torque and speed are smaller, the stability is higher, and the motor vibration and noise are lower.

[0033] Since the magnetic pole arc coefficient of the magnet is inversely proportional to the back electromotive force distortion rate, the larger the magnetic pole arc coefficient, the smaller the required edge thickness of the main magnet 2. Under the condition of ensuring the strength and processing accuracy of the magnet, the magnet cannot be made in a large size at the minimum processing thickness. After using the auxiliary magnet 3, the auxiliary magnet can be processed to the minimum thickness, ensuring the strength of the magnet, reducing the processing difficulty, and thereby reducing the back electromotive force distortion rate.

[0034] Preferably, the auxiliary magnet 3 has a tile-like structure. The inner surface curvature of the auxiliary magnet 3 is the same as its outer surface curvature and is simultaneously conformable to the outer wall curved surface of the rotor body 1. The auxiliary magnet 3 is closely attached to the outer wall of the rotor body 1, and its magnetization direction is consistent with the magnetization direction of the adjacent main magnet 2. Thus, in terms of structure only, the main magnet 2 and the two adjacent auxiliary magnets 3 can be regarded as a large magnet, which provides a continuous magnetic flux density perpendicular to the rotor to the air gap, increasing the stability during the operation of the motor.

[0035] Preferably, all the auxiliary magnets 3 in the rotor structure have the same size, and the processing of the auxiliary magnets 3 can be standardized, simplifying the magnet processing technology and improving the production efficiency.

[0036] Preferably, the main magnet 2 is adhesively bonded to the outer peripheral wall of the rotor body 1, and / or the auxiliary magnet 3 is adhesively bonded to the outer peripheral wall of the rotor body 1. The rotor structure further includes a binding band 4. The binding band 4 is wound around the surface of the main magnet 2. The binding band 4 binds the main magnet 2 to the outer peripheral wall of the rotor body 1, and an air gap of the motor is formed between the stator structure 5 and the binding band 4.

[0037] In another embodiment, the auxiliary magnet 3 and the main magnet 2 are of an integral structure, and the two are processed from a single piece of magnet.

[0038] As Figure 4 、 5 shown, in the magnetic circuit of the rotor structure of the prior art, F1 and F2 represent the magnetomotive forces generated by two magnets, and φm, φσ, and φ1 represent the total magnetic flux provided by the magnets, the interpolar leakage magnetic flux, and the magnetic flux entering the air gap, respectively. Figure 5 Among them, RO, Rσ, and R1 represent the internal magnetic resistance of the magnet, the interpolar leakage magnetic resistance, and the main magnetic resistance, respectively. According to Kirchhoff's law of magnetic circuits, it can be known that:

[0039] F1 + F2 = φmR0 + φσRσ (1)

[0040] φσRσ = φ1R1 (2)

[0041] Compared with the rotor structure of the prior art, in the rotor structure of this embodiment, the auxiliary magnet fills the gap of the main magnet, the interpolar leakage magnetic resistance Rσ increases, and the interpolar leakage magnetic flux decreases, improving the utilization rate of the permanent magnet and the efficiency of the motor.

[0042] In this embodiment, the magnetic lines of force at the edge of the main magnet 2 are far from the rotor body 1 and enter the air gap, reducing magnetic leakage, increasing the sinusoidal similarity of the line back electromotive force, reducing the distortion rate of the line back electromotive force of the motor, reducing the torque fluctuation during the load operation of the motor, and further reducing the vibration and noise of the motor, and improving the service life of the motor. At the same time, the auxiliary magnet 3 increases the magnetic flux density at the edge of the main magnet 2 and thus increases the back electromotive force constant of the motor.

[0043] The back electromotive force constant of the motor represents the ability of the motor to generate rotational torque per unit current. The larger this value, the greater the torque generated per unit current, thereby reducing the copper loss generated by the current in the motor and reducing the motor heating. Structurally, the permanent magnets on the rotor surface are closely attached to each other to form a whole, which not only strengthens the overall strength of the permanent magnets and avoids relative movement with the rotor, but also reduces the assembly difficulty of the rotor permanent magnets.

[0044] The permanent magnet structure of this embodiment can also effectively reduce the current under the rated torque of the motor, reduce the motor heating and vibration. Since the permanent magnets on the rotor are closely attached to each other, it can also improve the positioning accuracy of the rotor permanent magnets of the motor and reduce the motor assembly difficulty.

[0045] A motor adopts the above surface-mounted rotor structure.

[0046] It is easy for those skilled in the art to understand that, on the premise of no conflict, the above advantageous ways can be freely combined and superimposed.

[0047] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention. The above is only the preferred implementation manner of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and variations can be made, and these improvements and variations should also be regarded as the protection scope of the present invention.

Claims

1. A surface-mounted rotor structure, characterized in that, Comprising: Rotor body (1); A plurality of main magnets (2) are provided on the outer peripheral wall of the rotor body (1) at uniformly spaced intervals, and auxiliary magnets (3) are provided at both circumferential edges of the main magnets (2); the auxiliary magnets (3) have the same magnetization direction as the main magnets (2); Adjacent auxiliary magnets (3) are in contact with each other along the circumferential direction of the rotor body (1); The thickness of the main magnet (2) gradually decreases from the circumferential symmetry axis to both edges, and the thickness d1 of the auxiliary magnet (3) is equal to the edge thickness d2 of the main magnet (2).

2. The surface-mounted rotor structure according to claim 1, characterized in that The thickness d1 of the auxiliary magnet (3) and the edge thickness d2 of the main magnet (2) are less than or equal to 1.5 mm.

3. The surface-mounted rotor structure according to claim 1, characterized in that, The auxiliary magnet (3) has a tile-like structure, and the auxiliary magnet (3) is closely attached to the outer wall of the rotor body (1).

4. The surface-mounted rotor structure according to claim 1, wherein All the auxiliary magnets (3) in the rotor structure have the same size.

5. The surface-mounted rotor structure according to claim 1, characterized in that, The main magnet (2) is adhesively bonded to the outer peripheral wall of the rotor body (1), and / or the auxiliary magnet (3) is adhesively bonded to the outer peripheral wall of the rotor body (1).

6. The surface-mounted rotor structure according to claim 3, wherein The rotor structure further includes a binding band (4), and the binding band (4) is wound around the surface of the main magnet (2).

7. The surface-mounted rotor structure according to claim 1, characterized in that The auxiliary magnet (3) and the main magnet (2) are of an integral structure.

8. A motor, characterized in that, Adopt the surface-mounted rotor structure according to any one of claims 1-7.

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