Rotor punching sheet structure and permanent magnet synchronous motor

Abstract

The utility model discloses a rotor punching sheet structure, a permanent magnet (4) is arranged on a rotor punching sheet (1), a magnetic isolation bridge (5) is arranged on the surface of the rotor punching sheet (1), a plurality of groups of permanent magnet grooves (3) and air grooves (6) are arranged in the rotor punching sheet (1) at intervals along the circumferential direction, and rotor teeth (7) are connected between the end parts of the permanent magnet grooves (3) and the air grooves (6). A magnetic field generated by the permanent magnets (4) can interact with a magnetic field generated by stator current to generate stable permanent magnet torque, meanwhile, the formed permanent magnet grooves (3) and the air grooves (6) can remarkably improve the quadrature-direct axis inductance difference of the motor and improve the salient pole rate of the motor, so that stable output reluctance torque is guaranteed, all the permanent magnets (4) have the same polarity, and the permanent magnet torque is stable. And moreover, as no permanent magnet (4) is arranged in the air groove (6), the use amount of the permanent magnet (4) is theoretically reduced by 50%, and the manufacturing cost can be obviously reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of permanent magnet synchronous motors, and specifically relates to a rotor punching structure and a permanent magnet synchronous motor. Background Art

[0002] Permanent magnet synchronous motors using rare earth materials are one of the fastest growing motor types in recent years. With their advantages of high power density, low cost, and small size, they have been widely used in aerospace, electric vehicles, CNC machine tools, and other fields. Rare earth materials, as key materials for the processing and manufacturing of rare earth permanent magnet synchronous motors, are a non-renewable resource with limited reserves and high prices. Therefore, the development of permanent magnet synchronous motors with less rare earth or even no rare earth has become an important development direction in the field of motor design and manufacturing.

[0003] Generally speaking, for permanent magnet synchronous motors, their electromagnetic torque can be divided into permanent magnet torque and reluctance torque. If the permanent magnet on the rotor side is removed, the permanent magnet motor will be transformed into a synchronous reluctance motor, whose electromagnetic torque only contains reluctance torque components. It is an important type of rare earth-free motor. However, in order to generate a larger reluctance torque, the synchronous reluctance motor needs to open a large number of air magnetic barriers in the rotor punching to increase the motor salient pole ratio, so its mechanical strength is difficult to guarantee; in addition, compared with permanent magnet synchronous motors, synchronous reluctance motors need to provide additional excitation current from the stator current, so their power factor and efficiency are relatively low. The use of non-rare earth permanent magnet synchronous motors can effectively provide permanent magnet torque and reluctance torque. However, the remanence of non-rare earth materials is low, and the permanent magnet torque they can provide is relatively small. Therefore, the torque output still mainly relies on the reluctance torque, and its torque output capacity is much lower than that of traditional rare earth permanent magnet motors.

[0004] A public specification with application number 202111374554.4 and publication date of April 12, 2022 discloses a permanent magnet-assisted synchronous reluctance motor with an alternating salient pole rotor. A permanent magnet-assisted synchronous reluctance motor with an alternating salient pole rotor comprises a stator core, a stator winding, a rotor core, a permanent magnet, and a rotating shaft. Three-phase alternating current is passed through the stator winding to generate a changing magnetic field. The rotor core is a circularly symmetrical salient pole structure with a total of 8 protruding magnetic poles. Magnetic barriers are opened in the circumferential direction. A permanent magnet is placed every other magnetic barrier. Permanent magnets with the same polarity are placed in the magnetic barriers that are symmetrical about the axis center. The permanent magnets are ferrites, forming an alternating pole salient pole rotor. The permanent magnet-assisted synchronous reluctance motor using an alternating salient pole rotor improves the power factor.

[0005] In the above-mentioned prior art, the amount of permanent magnets used is high, the manufacturing cost is expensive, and a high electromagnetic torque cannot be guaranteed, which affects the output. Utility Model Content

[0006] The utility model aims to provide a rotor punching structure and a permanent magnet synchronous motor which can reduce the amount of permanent magnets as much as possible while ensuring a higher electromagnetic torque, thereby achieving a permanent magnet synchronous motor with both performance and cost taken into consideration.

[0007] In order to achieve the above-mentioned purpose, the technical solution adopted by the utility model is: a rotor punching structure, the rotor punching is provided with a permanent magnet and a permanent magnet slot matching the permanent magnet, the rotor punching is provided with an air slot distributed circumferentially with the permanent magnet slot, rotor teeth are connected between the ends of the permanent magnet slot and the air slot, and a magnetic isolation bridge is provided on the surface of the rotor punching.

[0008] The magnetic isolation bridge is located between the end of the permanent magnet slot and the outer edge of the rotor punching sheet, and the magnetic isolation bridge is also located between the end of the air slot and the outer edge of the rotor punching sheet.

[0009] The number of the permanent magnet slots and the air slots is the number of pole pairs of the permanent magnet synchronous motor.

[0010] The permanent magnet is rectangular, and the magnetization direction of the permanent magnet is perpendicular to the long side of the permanent magnet.

[0011] The rotor teeth are parallel teeth.

[0012] The thickness of the magnetic isolation bridge is 2mm-3mm.

[0013] The number of layers of the permanent magnet slots and the air slots along the radial direction of the rotor punching sheet is 1, the permanent magnet slots and the air slots are V-shaped, the angles on both sides of the permanent magnet slots range from 90° to 160°, and the angles on both sides of the air slots range from 90° to 160°.

[0014] The ratio of the thickness of the permanent magnet slot to the thickness of the air slot is 1.

[0015] The ratio of the width of the rotor teeth to the pole pitch of the permanent magnet synchronous motor is 0.2-0.3.

[0016] A permanent magnet synchronous motor comprises a rotor punching structure, wherein the rotor punching is provided with an axial hole matched with the rotor shaft of the permanent magnet synchronous motor, and the rotor punching is a silicon steel disc.

[0017] The technical effects of the utility model are as follows: a plurality of groups of permanent magnet slots and air slots are arranged in a circumferential direction inside the rotor punching sheet, wherein rectangular permanent magnets are embedded in the permanent magnet slots, and the permanent magnet slots and the air slots are connected by rotor teeth; the magnetic field generated by the permanent magnets can interact with the magnetic field generated by the stator current to generate a stable permanent magnet torque, and at the same time, the permanent magnet slots and air slots can significantly improve the inductance difference between the AC and DC axes of the motor and improve the salient pole rate of the motor, thereby ensuring a stable output reluctance torque;

[0018] The permanent magnet slots and air slots inside the rotor laminations are connected by thinner magnetic isolation bridges near the end of the rotor outer circle. On the basis of ensuring mechanical strength, the saturation of the magnetic isolation bridge can be effectively improved, the cross-linkage between the permanent magnet magnetic linkage and itself can be reduced, and the permanent magnet magnetic leakage can be reduced;

[0019] All permanent magnets have the same polarity, and are easy to manufacture. In addition, the amount of permanent magnets used is theoretically reduced by 50%, which can significantly reduce manufacturing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] This specification includes the following drawings, which show the following contents:

[0021] Figure 1 This is a schematic diagram of the structure of a rotor punching structure of the utility model;

[0022] Figure 2 It is the magnetic force line distribution diagram of the existing bipolar rotor permanent magnet synchronous motor finite element simulation;

[0023] Figure 3 This is a finite element simulation magnetic field line distribution diagram of a rotor punching structure and a single-polarity rotor permanent magnet synchronous motor of the utility model;

[0024] Figure 4 The finite element simulation torque comparison diagram of the existing bipolar rotor permanent magnet synchronous motor and the unipolar rotor permanent magnet synchronous motor of the utility model with a rotor punching structure and a permanent magnet synchronous motor.

[0025] The markings in the figure are: 1. rotor punching; 2. shaft hole; 3. permanent magnet slot; 4. permanent magnet; 5. magnetic isolation bridge; 6. air slot; 7. rotor tooth. DETAILED DESCRIPTION

[0026] The following is a further detailed description of the specific implementation methods of the utility model by describing the embodiments with reference to the accompanying drawings, with the aim of helping those skilled in the art to have a more complete, accurate and in-depth understanding of the utility model concept and technical solution of the utility model and facilitating its implementation.

[0027] A rotor punching structure is disclosed. A rotor punching 1 is provided with a permanent magnet 4 and a permanent magnet slot 3 matched with the permanent magnet 4. The rotor punching 1 is provided with an air slot 6 distributed circumferentially with the permanent magnet slot 3. Rotor teeth 7 are connected between the ends of the permanent magnet slot 3 and the air slot 6. A magnetic isolation bridge 5 is provided on the surface of the rotor punching 1.

[0028] Permanent magnet slots 3 and air slots 6 are spaced apart in the circumferential direction inside the rotor punching 1, and permanent magnets 4 are embedded in the permanent magnet slots 3, while permanent magnets 4 are not embedded in the air slots 6. This can reduce the amount of permanent magnets 4, that is, theoretically reduce the amount of permanent magnets 4 by 50%, increase the salient pole ratio of the motor, improve the reluctance torque output capacity, and ultimately ensure that the motor torque output is at a relatively high level.

[0029] The magnetic isolation bridge 5 is located between the end of the permanent magnet slot 3 and the outer edge of the rotor punching 1, and the magnetic isolation bridge 5 is also located between the end of the air slot 6 and the outer edge of the rotor punching 1; the permanent magnet slot 3 inside the rotor punching 1 and the end of the air slot 6 close to the outer edge of the rotor punching 1 are connected by a thinner magnetic isolation bridge 5, which can effectively improve the saturation of the magnetic isolation bridge 5 on the basis of ensuring mechanical strength, reduce the cross-linkage between the magnetic flux of the permanent magnet 4 and itself, and reduce the magnetic leakage of the permanent magnet 4.

[0030] The number of the permanent magnet slots 3 and the air slots 6 is the number of pole pairs of the permanent magnet synchronous motor.

[0031] The permanent magnet 4 is rectangular, and the magnetizing direction of the permanent magnet 4 is perpendicular to the long side of the permanent magnet 4; the long side of the permanent magnet 44 is 17.9 mm, the short side is 7.2 mm, and all the permanent magnets 4 have the same polarity. The magnetizing direction can effectively form a magnetic field focusing effect, so that the magnetic field of the permanent magnet 4 passes through the direct axis of the permanent magnet synchronous motor as much as possible, thereby improving the direct axis saturation and increasing the salient pole ratio.

[0032] The rotor teeth 7 are parallel teeth; the width of the rotor teeth 7 is 14 mm, which can effectively ensure the smoothness of the cross-axis magnetic circuit, improve the motor salient pole rate, and increase the torque output level.

[0033] The thickness of the magnetic isolation bridge 5 is 2mm-3mm; the actual thickness is 2mm. On the basis of ensuring mechanical strength, it can effectively improve the saturation of the magnetic isolation bridge 5, reduce the cross-linkage between the magnetic linkage of the permanent magnet 4 and itself, and reduce the leakage magnetic flux of the permanent magnet 4.

[0034] The number of layers of the permanent magnet slots 3 and the air slots 6 along the radial direction of the rotor punching 1 is 1, the permanent magnet slots 3 and the air slots 6 are V-shaped, the angle range of the permanent magnet slots 3 on both sides is 90°-160°, and the angle range of the air slots 6 on both sides is 90°-160°; the optimal angles of both are 145°. Combined with the magnetization direction of the rectangular permanent magnet 4 perpendicular to the long side of the rectangular permanent magnet 4, it can effectively form a magnetic field concentration effect, so that the magnetic field of the permanent magnet 4 passes through the direct axis of the permanent magnet synchronous motor as much as possible, thereby improving the direct axis saturation and increasing the salient pole rate.

[0035] The thickness ratio of the permanent magnet slot 3 and the air slot 6 is 1; the optimal thickness ratio is 1, and the optimal thicknesses of the permanent magnet slot 3 and the air slot 6 are both 7.2 mm, which can simplify the production steps and improve the production efficiency.

[0036] The ratio of the width of the rotor tooth 7 to the pole pitch of the permanent magnet synchronous motor is 0.2-0.3; the optimal ratio is 0.28, which can effectively ensure the smoothness of the cross-axis magnetic circuit, improve the motor salient pole rate, and increase the torque output level.

[0037] A permanent magnet synchronous motor comprises a rotor punching structure. A shaft hole 2 matching with the rotor shaft of the permanent magnet synchronous motor is provided on the rotor punching 1. The rotor punching 1 is a silicon steel disc.

[0038] like Figure 2 This is a comparison diagram of the magnetic lines of force of the existing bipolar rotor permanent magnet synchronous motor finite element simulation. Figure 3 This is the magnetic field line distribution diagram of the finite element simulation of the unipolar rotor permanent magnet synchronous motor of the utility model. Figure 2 and Figure 3 In the embodiment, the motor structure and size are not changed, only the bipolar rotor is changed to a unipolar rotor. From the comparison of the magnetic lines of force of the finite element simulation in the above two figures, it can be found that both rotor punching sheets 1 structures form 4 pairs of poles, and the distribution of magnetic lines of force is relatively consistent. It can be seen that the permanent magnet synchronous motor rotor punching sheet 1 in this embodiment can reduce the amount of permanent magnets 4 and still maintain the required number of magnetic poles.

[0039] like Figure 4 It is a finite element simulation torque comparison diagram of the existing bipolar rotor permanent magnet synchronous motor and the utility model unipolar rotor permanent magnet synchronous motor, in which the other structural dimensions of the motor have not changed, and the stator current remains the same; the average value of the torque generated by the existing bipolar rotor permanent magnet synchronous motor is 165.73Nm, and the torque pulsation is 27.93Nm; the average value of the torque generated by the utility model unipolar rotor permanent magnet synchronous motor is 121.59Nm, and the torque pulsation is 17.15Nm, which is 26.63% lower than the average value of the torque of the existing rotor scheme, and the torque pulsation is 38.5%. It can be seen that although the use of the utility model rotor punching 1 scheme will cause a significant decrease in torque pulsation, which is about 26.63% lower than the existing bipolar rotor permanent magnet synchronous motor, the amount of permanent magnet 4 is reduced by 50%, and the torque output is more stable, which can greatly reduce the torque pulsation.

[0040] The technical effects of the utility model are as follows: a plurality of groups of permanent magnet slots 3 and air slots 6 are arranged in a circumferential direction inside the rotor punching sheet 1, wherein the permanent magnet slots 3 are embedded with rectangular permanent magnets 4, and the permanent magnet slots 3 and the air slots 6 are connected by rotor teeth 7; the magnetic field generated by the permanent magnet 4 can interact with the magnetic field generated by the stator current to generate a stable permanent magnet torque, and at the same time, the permanent magnet slots 3 and the air slots 6 can significantly improve the inductance difference between the AC and DC axes of the motor and improve the salient pole rate of the motor, thereby ensuring a stable output reluctance torque;

[0041] The permanent magnet slots 3 and the air slots 6 inside the rotor punching 1 are connected by a thinner magnetic isolation bridge 5 near the end of the rotor outer circle. On the basis of ensuring mechanical strength, the saturation of the magnetic isolation bridge 5 can be effectively improved, the cross-linkage between the magnetic linkage of the permanent magnet 4 and itself can be reduced, and the magnetic leakage of the permanent magnet 4 can be reduced;

[0042] All permanent magnets 4 have the same polarity, and are easy to manufacture. In addition, the amount of permanent magnets 4 is theoretically reduced by 50%, which can significantly reduce manufacturing costs.

[0043] The above is an exemplary description of the utility model in conjunction with the accompanying drawings. Obviously, the specific implementation of the utility model is not limited to the above-mentioned method. As long as various non-substantial improvements are made using the method concept and technical solution of the utility model; or the above concept and technical solution of the utility model are directly applied to other occasions without improvement, they are all within the protection scope of the utility model.

Claims

1. A rotor punching structure, characterized in that: The rotor punching (1) is provided with a permanent magnet (4) and a permanent magnet slot (3) matched with the permanent magnet (4); the rotor punching (1) is provided with an air slot (6) distributed circumferentially with the permanent magnet slot (3); rotor teeth (7) are connected between the ends of the permanent magnet slot (3) and the air slot (6); and a magnetic isolation bridge (5) is provided on the surface of the rotor punching (1).

2. A rotor punching structure according to claim 1, characterized in that: The magnetic isolation bridge (5) is located between the end of the permanent magnet slot (3) and the outer edge of the rotor punching (1), and the magnetic isolation bridge (5) is also located between the end of the air slot (6) and the outer edge of the rotor punching (1).

3. A rotor punching structure according to claim 1 or 2, characterized in that: The number of the permanent magnet slots (3) and the air slots (6) is the number of pole pairs of the permanent magnet synchronous motor.

4. A rotor punching structure according to claim 1, characterized in that: The permanent magnet (4) is rectangular, and the magnetization direction of the permanent magnet (4) is perpendicular to the long side of the permanent magnet (4).

5. A rotor punching structure according to claim 1, characterized in that: The rotor teeth (7) are parallel teeth.

6. A rotor punching structure according to claim 1 or 2, characterized in that: The thickness of the magnetic isolation bridge (5) is 2 mm to 3 mm.

7. A rotor punching structure according to claim 3, characterized in that: The number of layers of the permanent magnet slots (3) and the air slots (6) along the radial direction of the rotor punching sheet (1) is 1; the permanent magnet slots (3) and the air slots (6) are V-shaped; the angles on both sides of the permanent magnet slots (3) are in the range of 90°-160°; and the angles on both sides of the air slots (6) are in the range of 90°-160°.

8. A rotor punching structure according to claim 1, 2 or 7, characterized in that: The ratio of the thickness of the permanent magnet slot (3) to the thickness of the air slot (6) is 1.

9. A rotor punching structure according to claim 1 or 5, characterized in that: The ratio of the width of the rotor teeth (7) to the pole pitch of the permanent magnet synchronous motor is 0.2-0.

3.

10. A permanent magnet synchronous motor, according to a rotor punching structure according to any one of claims 1 to 9, characterized in that: The rotor punching sheet (1) is provided with an axial hole (2) that matches the rotor shaft of the permanent magnet synchronous motor, and the rotor punching sheet (1) is a silicon steel disc.

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