Surface-mounted combined magnetic pole rotor structure for shielding motor

Abstract

The utility model discloses a surface-mounted combined magnetic pole rotor structure for a shielding motor, which comprises a rotor sheath, first permanent magnets and a second permanent magnet, and the first permanent magnets are arranged on the two sides of the second permanent magnet. And the residual magnetism of the first permanent magnet of each pole of combined permanent magnet is smaller than that of the second permanent magnet, so that the cogging torque can be effectively reduced, and the radial air gap flux density is more sinusoidal, thereby improving the sinusoidal property of the counter electromotive force and reducing the ripple torque of the motor. According to the rotor structure, the thickness of each permanent magnet is equal, the rotor sheath is in interference fit with the permanent magnets, the safety of the permanent magnets is more reliable, the stator does not need skewed slots, and the torque density and the power factor of the motor cannot be reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of electric motors, and in particular relates to a surface-mounted combined magnetic pole rotor structure for a shielded motor. Background Art

[0002] Permanent magnet shielded motors are often combined with pump bodies due to their high power density and high efficiency. They are mainly used to transport flammable, radioactive, toxic and other liquid media, and are often used in special fields such as petroleum, nuclear industry, aerospace, etc. Shielded motors have high speeds and their rotors are mostly surface-mounted structures. In order to prevent the permanent magnets from being thrown out due to centrifugal force and the liquid from corroding the permanent magnets, there are sheaths on the outside of the permanent magnets, and most of them are non-magnetic and highly conductive metal materials. In addition, when shielded motors are used in conjunction with pumps, higher requirements are placed on the torque fluctuations of the motors. According to motor theory, the torque fluctuations of the motors are mainly caused by the ripple torque generated by the action of the back-electromotive force harmonics and the stator current, and the tooth torque generated by the uneven air gap magnetic permeability. In order to reduce torque fluctuations, surface-mounted motors often use the methods of continuous stator skew slots and permanent magnet surface arc repair (uneven rotor air gap). However, these two methods have the following defects when applied to high-speed shielded motors:

[0003] 1. Special occasions have high requirements for motor power density. After the stator is continuously skewed, the leakage reactance of the skewed slots will reduce the motor power density and power factor;

[0004] 2. Stator skew slots are difficult to remove from production line. Especially for small-volume integral slot motors, the number of slots is small and the skew angle is large, which further increases the difficulty of removing from production line and reduces slot utilization;

[0005] 3. After the arc is repaired, the permanent magnet surface is in line contact with the rotor sleeve. When the rotor rotates at high speed, the sleeve has almost no pressure on the permanent magnet, and the permanent magnet is easily broken, with low reliability.

[0006] According to the previous analysis, the ripple torque can be reduced by reducing the back EMF harmonics and improving the sinusoidality of the back EMF; the cogging torque can be suppressed by reducing the rate of change of the magnetic field when the rotor passes through the tooth slots; and both of these physical quantities can be improved simultaneously by improving the sinusoidality of the radial air gap magnetic field. Summary of the invention

[0007] The purpose of the utility model is to overcome the above problems and propose a surface-mounted combined pole rotor structure for a shielded motor, which can reduce the harmonics of the radial air gap magnetic field, thereby improving the sinusoidality of the back electromotive force and reducing the cogging torque to improve the motor torque fluctuation.

[0008] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0009] The utility model provides a surface-mounted combined magnetic pole rotor structure for a shielded motor, comprising a permanent magnet, a rotor sheath arranged outside the permanent magnet, and a first permanent magnet and a second permanent magnet arranged on the permanent magnet.

[0010] A further improvement of the utility model is that the first permanent magnet and the second permanent magnet are arranged in a magnetic steel slot, and the magnetic steel slot is located on the rotor yoke.

[0011] A further improvement of the utility model is that the rotor sleeve adopts a metal non-magnetic sleeve, and the rotor sleeve is interference-fitted with the first permanent magnet and the second permanent magnet.

[0012] A further improvement of the utility model is that the remanent magnetism of the second permanent magnet is Br1, and the remanent magnetism of the first permanent magnet is Br2, wherein Br1>Br2.

[0013] A further improvement of the utility model is that the first permanent magnet comprises a left first permanent magnet and a right first permanent magnet.

[0014] A further improvement of the utility model is that the magnetization directions of the first permanent magnet on the left side, the first permanent magnet on the right side and the second permanent magnet are the same, that is, they are all magnetized in parallel.

[0015] A further improvement of the utility model is that the thickness of the first permanent magnet on the left side, the first permanent magnet on the right side and the second permanent magnet are the same.

[0016] A further improvement of the utility model is that the left first permanent magnet and the right first permanent magnet are respectively located on the left and right sides of the second permanent magnet.

[0017] A further improvement of the present invention is that the widths of the first permanent magnet on the left side, the first permanent magnet on the right side and the second permanent magnet are L1, L3 and L2 respectively, wherein L1=L3<L2.

[0018] Compared with the prior art, the utility model has the following beneficial effects:

[0019] The utility model arranges a rotor sleeve on the outside of the permanent magnet and arranges a second permanent magnet on the permanent magnet, thereby changing the traditional single-pole whole permanent magnet into a single-pole combined permanent magnet, which can not only effectively reduce the cogging torque, but also make the radial air gap magnetic density more sinusoidal, thereby improving the sinusoidality of the back electromotive force and reducing the motor ripple torque. The utility model has the advantages of safe and reliable permanent magnets and will not reduce the torque density and power factor of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the rotor structure of the utility model;

[0021] Figure 2 This is a schematic diagram of the magnetization direction of the N pole of the monopole combined permanent magnet of the utility model;

[0022] Figure 3 It is a schematic diagram of the magnetization direction of the S pole of the monopole combined permanent magnet of the utility model;

[0023] Figure 4 It is a schematic diagram of the comparison of the no-load back electromotive force between the combined magnetic pole of the utility model and the traditional magnetic pole;

[0024] Figure 5 A schematic diagram comparing the radial air gap magnetic flux density of the combined magnetic pole of the utility model and the traditional magnetic pole;

[0025] Figure 6 It is a schematic diagram of the comparison results of FFT decomposition of radial air gap magnetic flux density between the combined magnetic pole of the utility model and the traditional magnetic pole;

[0026] Figure 7 It is a schematic diagram of the comparison results of the cogging torque of the combined magnetic pole of the utility model and the traditional magnetic pole;

[0027] Figure 8 It is a schematic diagram of the comparison results of the electromagnetic torque of the combined magnetic pole of the utility model and the traditional magnetic pole.

[0028] Among them, 1. rotor sleeve; 2. first permanent magnet; 2-1 first permanent magnet on the left; 2-2 first permanent magnet on the right; 3. second permanent magnet 4. rotor yoke. DETAILED DESCRIPTION

[0029] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but it should not be understood that the above subject matter of the present invention is limited to the following embodiments. Without departing from the above technical ideas of the present invention, various substitutions and changes are made according to common technical knowledge and conventional means in the field, which should all be included in the protection scope of the present invention.

[0030] See also Figures 1 to 3 The utility model provides a surface mounted combined magnetic pole rotor structure for a shielded motor, comprising a rotor sleeve 1, a first permanent magnet 2, a second permanent magnet 3 and a rotor yoke 4.

[0031] A metal non-magnetic rotor sleeve 1 is arranged on the outside of the permanent magnet, a first permanent magnet 2 and a second permanent magnet 3 are arranged on the permanent magnet, the first permanent magnet 2 and the second permanent magnet 3 are arranged in a magnetic steel slot, the magnetic steel slot is located on the rotor yoke 4, the rotor sleeve 1 and the first permanent magnet 2 and the second permanent magnet 3 are interference fit, the permanent magnet is safer, the remanence of the second permanent magnet 3 is Br1, and the remanence of the first permanent magnet 2 is Br2, wherein Br1>Br2, which can not only effectively reduce the cogging torque, but also make the radial air gap magnetic flux more sinusoidal, thereby improving the sinusoidality of the back electromotive force and reducing the motor ripple torque.

[0032] The first permanent magnet 2 includes a first permanent magnet 2-1 on the left and a first permanent magnet 2-2 on the right. The first permanent magnet 2-1 on the left, the first permanent magnet 2-2 on the right and the second permanent magnet 3 have the same magnetization direction, which is parallel magnetization. The first permanent magnet 2-1 on the left, the first permanent magnet 2-2 on the right and the second permanent magnet 3 have the same thickness. The first permanent magnet 2-1 on the left and the first permanent magnet 2-2 on the right are respectively located on the left and right sides of the second permanent magnet 3. The widths of the first permanent magnet 2-1 on the left, the first permanent magnet 2-2 on the right and the second permanent magnet 3 are L1, L3 and L2 respectively, wherein L1=L3<L2. The values ​​of L1, L2, L3, Br1 and Br2 are interrelated and related to the motor torque fluctuation and the cogging torque. Their specific values ​​can be calculated by multi-objective optimization combined with the finite element method.

[0033] Working principle:

[0034] By analyzing the generation principle of cogging torque and ripple torque of permanent magnet motor, it can be known that by changing the sinusoidal nature of radial air gap flux density, cogging torque and ripple torque can be effectively weakened at the same time. Based on this, the traditional single-pole whole permanent magnet is changed to a single-pole combined permanent magnet, and the remanent magnetism of the permanent magnets on both sides of each pole combined permanent magnet is smaller than that of the middle permanent magnet. This structure is similar to the principle of improving the sinusoidal nature of radial air gap flux density with the rotor uneven air gap structure. Compared with the permanent magnet uneven air gap structure, the structure proposed in this patent has a large contact area between the rotor sleeve and the permanent magnet, and the reliability of the permanent magnet is good.

[0035] The characteristics of the rotor structure proposed in this patent are further explained through finite element calculation. The finite element calculation results can be found in Figures 4 to 8 It should be noted that the model used in the following result comparison is only different in the rotor structure, and the other parameters and physical quantities are exactly the same. Through the above comparative analysis, it can be seen that the combined magnetic pole structure can effectively improve the sinusoidality of the radial air gap flux density and reduce the motor torque fluctuation and cogging torque compared with the traditional magnetic pole structure.

[0036] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field can still modify or replace the specific implementation methods of the present invention. Any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention are within the scope of protection of the claims of the present invention to be approved.

Claims

1. A surface mounted combined pole rotor structure for a shielded motor, characterized in that: It comprises a permanent magnet, a rotor sleeve (1) is arranged outside the permanent magnet, and a first permanent magnet (2) and a second permanent magnet (3) are arranged on the permanent magnet.

2. The surface mounted combined pole rotor structure for a shielded motor according to claim 1, characterized in that: The first permanent magnet (2) and the second permanent magnet (3) are arranged in magnetic steel slots, and the magnetic steel slots are located on the rotor yoke (4).

3. The surface mounted combined pole rotor structure for a shielded motor according to claim 1, characterized in that: The rotor sleeve (1) is a metal non-magnetic sleeve, and the rotor sleeve (1) is interference-fitted with the first permanent magnet (2) and the second permanent magnet (3).

4. The surface mounted combined magnetic pole rotor structure for a shielded motor according to claim 1, characterized in that: The remanent magnetism of the second permanent magnet (3) is Br1, and the remanent magnetism of the first permanent magnet (2) is Br2, wherein Br1>Br2.

5. The surface mounted combined magnetic pole rotor structure for a shielded motor according to claim 1, characterized in that: The first permanent magnet (2) includes a left first permanent magnet (2-1) and a right first permanent magnet (2-2).

6. The surface mounted combined magnetic pole rotor structure for a shielded motor according to claim 5, characterized in that: The first permanent magnet (2-1) on the left, the first permanent magnet (2-2) on the right and the second permanent magnet (3) have the same magnetization direction, which is parallel magnetization.

7. The surface mounted combined magnetic pole rotor structure for a shielded motor according to claim 5, characterized in that: The thicknesses of the left first permanent magnet (2-1), the right first permanent magnet (2-2) and the second permanent magnet (3) are the same.

8. The surface mounted combined magnetic pole rotor structure for a shielded motor according to claim 5, characterized in that: The left first permanent magnet (2-1) and the right first permanent magnet (2-2) are respectively located on the left and right sides of the second permanent magnet (3).

9. The surface mounted combined magnetic pole rotor structure for a shielded motor according to claim 5, characterized in that: The widths of the first permanent magnet (2-1) on the left, the first permanent magnet (2-2) on the right, and the second permanent magnet (3) are L1, L3, and L2, respectively, wherein L1=L3<L2.

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