Built-in permanent magnet rotor structure based on oriented silicon steel

Abstract

The invention discloses a built-in permanent magnet rotor structure based on oriented silicon steel, belongs to the technical field of motors, and aims to solve the problem that the oriented silicon steel technology is limited in the existing rotor structure. The motor rotor comprises a rotor core and permanent magnets. The rotor iron core is a hollow cylinder formed by laminating m iron core laminations along the axial direction of the rotor, and each iron core lamination is formed by splicing 2n oriented silicon steel sheets along the circumferential direction of the iron core; m oriented silicon steel sheets which are axially laminated serve as a group of oriented silicon steel laminations, every two adjacent groups of oriented silicon steel laminations form a permanent magnet rotor splicing unit, n permanent magnet rotor splicing units are arranged in the circumferential direction, and a permanent magnet is axially inserted between every two groups of oriented silicon steel laminations in each permanent magnet rotor splicing unit. By selecting the proper orientation direction of the oriented silicon steel sheet, the orientation direction of the oriented silicon steel is consistent with the main magnetic flux direction, the magnetic performance advantage of the oriented silicon steel in the orientation direction is fully played, the magnetic leakage is reduced, the output torque of the motor is improved, and the rotor iron loss is reduced.

Description

Technical Field

[0001] The present invention relates to an interior permanent magnet rotor structure based on grain-oriented silicon steel, belonging to the technical field of motors. Background Art

[0002] Permanent magnet synchronous motors use permanent magnets for excitation without external excitation, and have the advantages of simple structure, low maintenance cost, high efficiency, high power density, high speed range, low noise, etc. They can provide stable power output and are suitable for occasions requiring high dynamic performance and precise control. The interior permanent magnet synchronous motor directly embeds the permanent magnets into the rotor, making the overall structure of the machine more compact and smaller in size, further improving the power density and torque density of the motor. It has been widely used in fields such as electric vehicles, power tools, and household appliances.

[0003] The rotor core of a motor is generally made of silicon steel, and silicon steel materials can be divided into non-oriented silicon steel and grain-oriented silicon steel. The grains of non-oriented silicon steel are isotropically distributed in the material, so its magnetic properties are basically the same in any direction. Traditional motor rotors are made of non-oriented silicon steel. Grain-oriented silicon steel is a silicon steel material with strong grain orientation after special processing. Its grains show obvious orientation in the material, making the material have more excellent magnetic properties in its orientation direction, but its magnetic properties in the non-orientation direction are poor. It is widely used in transformer cores. Generally speaking, in the orientation direction of grain-oriented silicon steel, its magnetic permeability is higher than that of non-oriented silicon steel, and its iron loss coefficient is smaller than that of non-oriented silicon steel. However, in the non-orientation direction of grain-oriented silicon steel, its magnetic permeability is lower than that of non-oriented silicon steel, and its iron loss coefficient is larger than that of non-oriented silicon steel. Therefore, only by using grain-oriented silicon steel on a specific rotor structure and selecting a suitable orientation direction can the motor torque be increased and the rotor iron loss be reduced.

[0004] Due to the anisotropic magnetic properties of grain-oriented silicon steel, improper use will deteriorate the motor performance, so it is rarely used in motors. Currently, it is only used in the stator of motors and the rotor of reluctance motors. In the motor of patent CN202311031686.6, the stator teeth of the motor are made of grain-oriented silicon steel, while the stator yoke is still made of non-oriented silicon steel. The salient pole rotor of the motor in patent CN202111047433.9 is made of grain-oriented silicon steel integrally, and the orientation direction is the radial direction of the rotor. This orientation direction is fixed and has poor flexibility, resulting in limited application in the rotor. Summary of the Invention

[0005] Aiming at the problem of limited application of grain-oriented silicon steel technology in the existing rotor structure, the present invention provides an interior permanent magnet rotor structure based on grain-oriented silicon steel. Through the design of a special structure and the selection of the orientation direction of grain-oriented silicon steel, the main magnetic flux direction is made consistent with the orientation direction of grain-oriented silicon steel, which can reduce magnetic leakage, help improve the output torque of the motor and reduce the rotor iron loss.

[0006] The internal permanent magnet rotor structure based on grain-oriented silicon steel of the present invention, the rotor structure includes a rotor core and a permanent magnet 2; the rotor core is formed by laminating m core laminations 1 along the axial direction of the rotor to form a hollow cylinder, and each core lamination 1 is composed of 2n grain-oriented silicon steel sheets 3 spliced along the circumferential direction of the core; the m grain-oriented silicon steel sheets 3 laminated axially are used as a group of grain-oriented silicon steel laminations, and two adjacent groups of grain-oriented silicon steel laminations form a permanent magnet rotor splicing unit 4. There are a total of n permanent magnet rotor splicing units 4 in the circumferential direction, and a permanent magnet 2 is axially inserted between the two groups of grain-oriented silicon steel laminations in the permanent magnet rotor splicing unit 4.

[0007] Preferably, the magnetization direction of the permanent magnet 2 is tangential.

[0008] Preferably, the orientation direction of the grain-oriented silicon steel sheet 3 is between 0° and 90°. In the permanent magnet rotor splicing unit 4, the direction from the center of the rotor to the center of the permanent magnet 2 is defined as the 0° direction, and the direction perpendicular to the 0° direction and pointing outward to both sides of the grain-oriented silicon steel sheet 3 is defined as the 90° direction.

[0009] Preferably, in the permanent magnet rotor splicing unit 4, the two grain-oriented silicon steel sheets 3 on the same core lamination 1 are symmetrically arranged, and the splicing line of the two grain-oriented silicon steel sheets 3 coincides with the permanent magnet center line pointing from the center of the rotor to the center of the permanent magnet.

[0010] Preferably, the orientation directions of the grain-oriented silicon steel sheets 3 on both sides of each permanent magnet 2 are symmetric about the permanent magnet 2 and are consistent with the main magnetic flux direction.

[0011] Preferably, in the permanent magnet rotor splicing unit 4, the two grain-oriented silicon steel sheets 3 on the same core lamination 1 are asymmetrically arranged, the sizes and shapes of the grain-oriented silicon steel sheets 3 on both sides of the permanent magnet 2 are different, and the splicing line of the two grain-oriented silicon steel sheets 3 coincides with the edge of the permanent magnet 2.

[0012] Preferably, the orientation directions of the grain-oriented silicon steel sheets 3 on both sides of each permanent magnet 2 are asymmetric about the permanent magnet 2, and the orientation direction on each side is consistent with the main magnetic flux direction on that side.

[0013] Preferably, the radial width of the permanent magnet 2 is greater than the width of the magnetic bridge part of the rotor core on both sides of it.

[0014] The beneficial effects of the present invention: The silicon steel sheets in the rotor core proposed by the present invention are spliced with grain-oriented silicon steel. By designing the rotor structure and selecting a suitable orientation direction, the main magnetic flux direction is made consistent with the orientation direction of the grain-oriented silicon steel, giving full play to the magnetic performance advantages of the grain-oriented silicon steel in its orientation direction, which can reduce magnetic leakage, help improve the output torque of the motor and reduce the loss of the rotor core. Description of the Drawings

[0015] Figure 1is a perspective view of an interior permanent magnet rotor structure based on grain-oriented silicon steel according to the present invention;

[0016] Figure 2 is a schematic diagram of the orientation range of the grain-oriented silicon steel according to the present invention;

[0017] Figure 3 is a schematic diagram of a symmetrical grain-oriented silicon steel permanent magnet rotor structure according to the present invention;

[0018] Figure 4 is a schematic diagram of a splicing unit of the symmetrical grain-oriented silicon steel permanent magnet rotor according to the present invention;

[0019] Figure 5 is a schematic diagram of an asymmetrical grain-oriented silicon steel permanent magnet rotor structure according to the present invention;

[0020] Figure 6 is a schematic diagram of a splicing unit of the asymmetrical grain-oriented silicon steel permanent magnet rotor according to the present invention;

[0021] Figure 7 is a distribution diagram of magnetic field lines when a non-oriented silicon steel permanent magnet rotor is under a small load;

[0022] Figure 8 is a distribution diagram of magnetic field lines when a non-oriented silicon steel permanent magnet rotor is under a large load. Detailed implementation manners

[0023] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the 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.

[0024] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other.

[0025] Next, the present invention will be further described in conjunction with the accompanying drawings and specific embodiments, but it is not a limitation of the present invention.

[0026] Detailed implementation manner one: Next, in conjunction with Figures 1 to 8To describe this embodiment, in the built-in permanent magnet rotor structure based on grain-oriented silicon steel described in this embodiment, the rotor structure includes a rotor core and a permanent magnet 2; the rotor core is formed by laminating m core laminations 1 along the rotor axis to form a hollow cylinder, and each core lamination 1 is composed of 2n grain-oriented silicon steel sheets 3 spliced along the circumference of the core; the m grain-oriented silicon steel sheets 3 laminated axially are used as a group of grain-oriented silicon steel laminations, and adjacent two groups of grain-oriented silicon steel laminations form a permanent magnet rotor splicing unit 4. There are a total of n permanent magnet rotor splicing units 4 in the circumferential direction, and a permanent magnet 2 is axially inserted between the two groups of grain-oriented silicon steel laminations in the permanent magnet rotor splicing unit 4.

[0027] The magnetization direction of the permanent magnet 2 is tangential.

[0028] The orientation direction of the grain-oriented silicon steel sheet 3 is between 0° and 90°. In the permanent magnet rotor splicing unit 4, the direction from the center of the rotor to the center of the permanent magnet 2 is defined as the 0° direction, and the direction perpendicular to the 0° direction and pointing outward to both sides of the grain-oriented silicon steel sheet 3 is defined as the 90° direction. For the definition principle, see Figure 2 as shown.

[0029] The rotor of the present invention has two types of structures: a symmetric grain-oriented silicon steel permanent magnet rotor and an asymmetric grain-oriented silicon steel permanent magnet rotor.

[0030] Among them, for the symmetric grain-oriented silicon steel permanent magnet rotor, see Figure 3 and Figure 4 , in the permanent magnet rotor splicing unit 4, the two grain-oriented silicon steel sheets 3 on the same core lamination 1 are symmetrically arranged, and the splicing line of the two grain-oriented silicon steel sheets 3 coincides with the permanent magnet center line pointing from the center of the rotor to the center of the permanent magnet.

[0031] The orientation directions of the grain-oriented silicon steel sheets 3 on both sides of each permanent magnet 2 are symmetric about the permanent magnet 2 and are consistent with the main magnetic flux direction.

[0032] For the other asymmetric grain-oriented silicon steel permanent magnet rotor, see Figure 5 and Figure 6 , in the permanent magnet rotor splicing unit 4, the two grain-oriented silicon steel sheets 3 on the same core lamination 1 are asymmetrically arranged, and the sizes and shapes of the grain-oriented silicon steel sheets 3 on both sides of the permanent magnet 2 are different, and the splicing line of the two grain-oriented silicon steel sheets 3 coincides with the edge of the permanent magnet 2.

[0033] The orientation directions of the grain-oriented silicon steel sheets 3 on both sides of each permanent magnet 2 are asymmetric about the permanent magnet 2, and the orientation direction on each side is respectively consistent with the main magnetic flux direction on that side.

[0034] The radial width of the permanent magnet 2 is greater than the width of the magnetic bridge part of the rotor core on both sides of it. The purpose of such a setting is to reduce magnetic leakage.

[0035] The following specific embodiments are given for two types of rotor structures. When conducting the actual motor design, the magnetic flux line distribution of the rotor using non-oriented silicon steel can be obtained based on theoretical and simulation analyses, so as to select the symmetric and asymmetric oriented silicon steel permanent magnet rotor structures and determine the orientation directions.

[0036] Embodiment 1

[0037] When the motor load is small, that is, when the three-phase current is small, the magnetic flux line distribution of the non-oriented silicon steel permanent magnet rotor is as Figure 7 shown. It can be seen from the figure that at this time, the magnetic flux lines on both sides of each permanent magnet are generally symmetrically distributed. Therefore, the symmetrically oriented silicon steel permanent magnet rotor structure of the present invention can be adopted at this time, and its orientation direction is set as the magnetic flux line direction of the main magnetic flux.

[0038] When the symmetrically oriented silicon steel permanent magnet rotor structure is adopted, the main magnetic flux direction is the orientation direction of the oriented silicon steel. The magnetic permeability in this direction is larger than that of the non-oriented silicon steel, so the main magnetic flux can be enhanced, thereby improving the output torque of the motor; at the same time, the direction of the leakage magnetic flux on the magnetic bridges on both sides of the permanent magnet 2 is between the orientation direction and the non-orientation direction, and is more biased towards the non-orientation direction. Therefore, the magnetic permeability in this direction is smaller than that of the non-oriented silicon steel, which helps to reduce the leakage magnetic flux. In addition, the iron loss coefficient of the oriented silicon steel in its orientation direction is smaller, so this structure can also reduce the iron loss.

[0039] Embodiment 2

[0040] When the motor load is large, that is, when the three-phase current is large, the magnetic flux line distribution of the non-oriented silicon steel permanent magnet rotor is as Figure 8 shown. It can be seen from the figure that at this time, the magnetic flux lines on both sides of each permanent magnet 2 show a strong asymmetric distribution. Therefore, the asymmetrically oriented silicon steel permanent magnet rotor structure of the present invention can be adopted at this time, and the orientation directions of the oriented silicon steel sheets on both sides of each permanent magnet 2 are set as the magnetic flux line directions of their respective main magnetic fluxes.

[0041] When the asymmetrically oriented silicon steel permanent magnet rotor structure is adopted, the orientation directions of the oriented silicon steel sheets on both sides of the permanent magnet 2 are respectively the main magnetic flux directions. The magnetic permeability in this direction is larger than that of the non-oriented silicon steel, which can enhance the main magnetic flux and thus improve the output torque of the motor; at the same time, through the design of the asymmetric structure, the magnetic bridges on both sides of the permanent magnet are on the silicon steel sheets with a smaller orientation angle. Therefore, the direction of the leakage magnetic flux is between the orientation direction and the non-orientation direction, and is more biased towards the non-orientation direction. The magnetic permeability in this direction is smaller than that of the non-oriented silicon steel, which helps to reduce the leakage magnetic flux. Since the iron loss coefficient of the oriented silicon steel in its orientation direction is smaller, this structure can also reduce the iron loss.

[0042] The internal permanent magnet rotor structure based on grain-oriented silicon steel according to the present invention, through the design of the rotor structure and the selection of a suitable orientation direction, makes the main magnetic flux direction consistent with the orientation direction of the grain-oriented silicon steel, fully exerts the magnetic property advantages of the grain-oriented silicon steel in its orientation direction, can reduce magnetic leakage, helps to improve the output torque of the motor and reduce the rotor iron loss.

[0043] The above has introduced in detail an internal permanent magnet rotor structure based on grain-oriented silicon steel proposed for the present invention. This article uses specific cases to elaborate on the principle and implementation manner of the present invention. The above cases are only used to help clarify the method and core idea of the present invention. For those of ordinary skill in the art, according to the concept of the present invention, there may be changes in the specific implementation and application scope. Therefore, the content of this specification should not be regarded as a limitation to the present invention.

Claims

1. A built-in permanent magnet rotor structure based on oriented silicon steel, characterized in that: The rotor structure comprises a rotor core and a permanent magnet (2); the rotor core is formed by stacking m core laminations (1) along the rotor axial direction to form a hollow cylinder, and each core lamination (1) is formed by splicing 2n oriented silicon steel sheets 3 along the circumferential direction of the core; the m axially stacked oriented silicon steel sheets (3) serve as a group of oriented silicon steel laminations, two adjacent groups of oriented silicon steel laminations constitute a permanent magnet rotor splicing unit (4), and there are a total of n permanent magnet rotor splicing units (4) in the circumferential direction; a permanent magnet (2) is axially inserted between two groups of oriented silicon steel laminations in the permanent magnet rotor splicing unit (4).

2. According to claim 1, a built-in permanent magnet rotor structure based on oriented silicon steel, characterized in that: The magnetization direction of the permanent magnet (2) is tangential.

3. The internal permanent magnet rotor structure based on oriented silicon steel according to claim 2, characterized in that: The orientation direction of the oriented silicon steel sheet (3) is between 0° and 90°. In the permanent magnet rotor splicing unit (4), the direction from the center of the rotor to the center of the permanent magnet (2) is defined as the 0° direction, and the direction perpendicular to the 0° direction and pointing outward to the oriented silicon steel sheets (3) on both sides is defined as the 90° direction.

4. The internal permanent magnet rotor structure based on oriented silicon steel according to claim 3, characterized in that: In the permanent magnet rotor splicing unit (4), two oriented silicon steel sheets (3) on the same iron core lamination (1) are symmetrically arranged, and the splicing line of the two oriented silicon steel sheets (3) coincides with the center line of the permanent magnet with the center of the rotor pointing to the center of the permanent magnet.

5. The interior permanent magnet rotor structure based on oriented silicon steel according to claim 4, characterized in that: The orientation directions of the oriented silicon steel sheets (3) on both sides of each permanent magnet (2) are symmetrical about the permanent magnet (2) and consistent with the direction of the main magnetic flux.

6. The interior permanent magnet rotor structure based on oriented silicon steel according to claim 3, characterized in that: In the permanent magnet rotor splicing unit (4), two oriented silicon steel sheets (3) on the same iron core lamination (1) are arranged asymmetrically, the oriented silicon steel sheets (3) on both sides of the permanent magnet (2) are different in size and shape, and the splicing line of the two oriented silicon steel sheets (3) coincides with the edge of the permanent magnet (2).

7. The interior permanent magnet rotor structure based on oriented silicon steel according to claim 6, characterized in that: The orientation directions of the oriented silicon steel sheets (3) on both sides of each permanent magnet (2) are asymmetric with respect to the permanent magnet (2), and the orientation direction of each side is respectively consistent with the main magnetic flux direction of that side.

8. The interior permanent magnet rotor structure based on oriented silicon steel according to any one of claims 1 to 7, characterized in that: The radial width of the permanent magnet (2) is greater than the width of the rotor core magnetic bridge parts on both sides thereof.

Images