A rotor structure for reducing electromagnetic exciting force of a permanent magnet motor

Abstract

The utility model provides a kind of rotor structure for reducing permanent magnet motor electromagnetic vibration force, belong to motor technical field.Solve the technical problem of excessive electromagnetic vibration force and excessive vibration noise caused by retaining the original asynchronous motor unskewed stator when asynchronous motor is transformed into permanent magnet motor.It includes rotating shaft, end plate, permanent magnet and rotor core, the rotor core is formed by a plurality of stamping pieces, a plurality of stamping piece slots are formed after stacking, the permanent magnet is embedded in the stamping piece slot, the rotating shaft is installed in the inner hole of the rotor core, the end plate is arranged at the axial ends of the rotor core, the stamping piece is provided with air magnetic bridge, the air magnetic bridge is arranged along the outer circle direction of the stamping piece, and the extension shape of the air magnetic bridge matches the outer circle arc of the stamping piece.It is mainly used for reducing the electromagnetic vibration and noise of the permanent magnet motor transformed from asynchronous motor.

Description

Technical Field

[0001] This utility model belongs to the field of electric motor technology, and in particular relates to a rotor structure for reducing the electromagnetic excitation force of a permanent magnet motor. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) are widely used in new energy vehicles, medical devices, and the military industry due to their advantages such as high power density, high efficiency, and excellent speed regulation performance. With the expansion of application scenarios, their vibration and noise performance is increasingly becoming a key indicator, especially in fields with stringent requirements for vibration and noise control. The vibration and noise of PSMs involves multiple disciplines, including mechanical structure, electromagnetic fields, fluid mechanics, acoustic propagation, and materials science, and can be mainly classified into three categories: mechanical noise, aerodynamic noise, and electromagnetic noise.

[0003] Mechanical noise originates from friction and impact between components, such as bearings, rotors, or moving parts of the ventilation system. This noise can be suppressed through material selection and optimized processing techniques. Aerodynamic noise is caused by pressure changes induced by airflow disturbances from the cooling fan and rotor, and can be improved by adjusting the fan blades and duct structure. Electromagnetic noise, as a major component of motor noise, often exhibits harsh high-frequency characteristics. Its root cause lies in the air gap harmonic magnetic field and the magnetostrictive effect of ferromagnetic materials. When the harmonic magnetic flux density of the stator and rotor teeth interacts, radial and tangential electromagnetic force components are generated. The radial electromagnetic force acts on the stator tooth surface, causing radial deformation displacement of the stator yoke, while the tangential electromagnetic force induces additional deformation through the stator tooth root bending moment. Both contribute to vibration noise. Therefore, reducing the radial electromagnetic force is an effective way to suppress motor vibration noise.

[0004] To improve system energy efficiency, users generally prefer to use permanent magnet motors instead of asynchronous motors. However, directly replacing an operational asynchronous motor with a permanent magnet motor results in resource waste. Therefore, converting an asynchronous motor into a permanent magnet motor has become the main method for energy-saving retrofits. In the rotor structure of an integrated permanent magnet motor, the core is made of 0.5mm silicon steel laminations to suppress eddy current losses. Rectangular permanent magnets are embedded in the lamination slots, and the shaft is fixed to the inner hole of the core via a heat-shrinking process. End plates are provided at both ends for axial fixation.

[0005] In retrofitting practices, to control costs, the original asynchronous motor stator structure is usually retained, and only the permanent magnet rotor is replaced. However, asynchronous motor stators often do not employ a skewed slot design, leading to significant vibration and noise in the retrofitted motor due to stator-rotor structural mismatch. The root cause is that if the permanent magnet motor rotor is skewed (axial misalignment of laminations), rectangular permanent magnets cannot be installed, and custom-made magnets with special shapes face drawbacks such as excessive cost, reduced magnetic circuit symmetry, and decreased mechanical strength. Therefore, conventional permanent magnet motor designs employ a stator skewed slot and rotor flat slot structure. When retrofitting projects retain the original flat slot stator, the lack of a skewed slot structure amplifies the magnetic field harmonic effects, causing a sharp increase in radial electromagnetic force and resulting in worsened vibration and noise. Utility Model Content

[0006] In view of this, the present invention aims to propose a rotor structure that reduces the electromagnetic excitation force of a permanent magnet motor, so as to solve the technical problem of excessive electromagnetic excitation force and excessive vibration noise caused by retaining the original asynchronous motor's non-skewed stator when converting an asynchronous motor into a permanent magnet motor.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a rotor structure for reducing the electromagnetic excitation force of a permanent magnet motor, comprising a rotating shaft, end plates, permanent magnets, and a rotor core. The rotor core is formed by stacking multiple stamped laminations, which together form multiple lamination slots evenly distributed along the circumferential direction. The permanent magnets are embedded in the lamination slots. The rotating shaft is installed in the inner hole of the rotor core. The end plates are located at both axial ends of the rotor core. Air magnetic bridges are provided on the stamped laminations, extending along the outer circumference of the stamped laminations. The extension shape of the air magnetic bridges matches the outer circumference of the stamped laminations.

[0008] Furthermore, the permanent magnet has a cuboid structure.

[0009] Furthermore, the permanent magnets are arranged in a V-shape.

[0010] Furthermore, the stamped sheet is made of silicon steel.

[0011] Furthermore, the thickness of the stamped sheet is 0.5 mm.

[0012] Furthermore, the rotating shaft is fixed in the inner hole of the rotor core by a heat-shrink fitting.

[0013] Compared with the prior art, the beneficial effects of this utility model are: 1. This utility model optimizes the magnetic resistance distribution of the main magnetic circuit and leakage magnetic circuit by setting the air magnetic bridge on the stamping sheet to extend along the outer circle of the stamping sheet, effectively reducing the high-order harmonic content in the air gap magnetic field, thereby reducing the radial electromagnetic force acting on the stator tooth surface from the source, and significantly improving the electromagnetic vibration and noise problems caused by the stator not using skewed slots in permanent magnet motors directly modified from asynchronous motors. 2. This utility model uses a V-shaped arrangement to embed rectangular permanent magnets. This structure enhances the symmetry of the magnetic circuit and the uniformity of the magnetic field distribution without excessively increasing the complexity of the process. It helps to further balance electromagnetic force waves, reduce torque pulsation, and has a positive effect on suppressing motor vibration. 3. The rotor core of this utility model adopts a straight slot structure and is matched with the optimized lamination slot shape, so that the rotor structure can be directly replaced into the original asynchronous motor stator without the need to modify the stator by slanting slots. This solves the problem that permanent magnet rotors cannot be used in retrofit projects due to the difficulty and high cost of slanting pole process, and realizes low-cost and high-efficiency motor energy-saving retrofit. 4. The overall rotor structure of this utility model is innovatively designed based on the original asynchronous motor laminations, which retains the versatility to the greatest extent. Its structural improvement focuses on the modification of the lamination mold, which is easy to achieve mass production. Attached Figure Description

[0014] The accompanying drawings, which form part of this utility model, are used to provide a further understanding of the utility model. The illustrative embodiments of the utility model and their descriptions are used to explain the utility model and do not constitute an undue limitation of the utility model. In the drawings: Figure 1 A schematic diagram of the rotor of a built-in permanent magnet motor; Figure 2 This is a partial structural diagram of the stamping sheet of a rotor structure for reducing electromagnetic excitation force of a permanent magnet motor, as described in this utility model.

[0015] In the picture: 1. Shaft; 2. End plate; 3. Permanent magnet; 4. Rotor core; 5. Stamped lamination; 6. Air-insulated magnetic bridge. Detailed Implementation

[0016] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present utility model can be combined with each other, and the described embodiments are only some embodiments of the present utility model, not all embodiments.

[0017] Detailed implementation method: See Figure 1-2This embodiment describes a rotor structure for reducing the electromagnetic excitation force of a permanent magnet motor, comprising a shaft 1, end plates 2, permanent magnets 3, and a rotor core 4. The rotor core 4 is formed by stacking multiple stamped laminations 5, which together form multiple lamination slots evenly distributed along the circumferential direction. The permanent magnets 3 are embedded in the lamination slots. The shaft 1 is installed in the inner hole of the rotor core 4. The end plates 2 are located at both axial ends of the rotor core 4. Air magnetic bridges 6 are provided on the stamped laminations 5. The air magnetic bridge 6 extends along the outer circle of the stamping sheet 5. The extended shape of the air magnetic bridge 6 matches the outer circle arc of the stamping sheet 5. The rotating shaft 1 serves as the core support component for rotor rotation. The end plate 2 is used to axially constrain the rotor core 4. The permanent magnet 3 is used to provide the excitation magnetic field. The rotor core 4 is the magnetic circuit carrier and does not provide installation space for the permanent magnet 3. After the permanent magnet 3 is embedded in the stamping groove, a magnetic circuit is formed. The air magnetic bridge 6 is used to block the magnetic circuit and change the distribution of magnetic lines of force.

[0018] This invention modifies the shape of the stamping plate 5 without changing the mechanical structure of the rotor. Based on the original groove shape of the rotor stamping plate 5, the shape of the air magnetic bridge 6 is extended along the outer circle of the stamping plate 5. This structure changes the magnetic circuit direction and increases the sinusoidal magnetic flux density, thereby reducing torque waveform pulsation and tooth electromagnetic excitation force, and thus reducing motor vibration noise.

[0019] The permanent magnet 3 has a cuboid structure. The cuboid permanent magnet 3, together with the air magnetic bridge 6 extending from the outer edge, coordinates to adjust the direction of the magnetic field lines, blocks short-circuit magnetic flux, and thus optimizes the magnetic field waveform.

[0020] The permanent magnets 3 are arranged in a V-shape. The V-shaped arrangement of the permanent magnets 3 and the air magnetic bridge 6 work together to constrain the leakage magnetic path and regulate the magnetic field distribution, directly suppressing the peak value of the tooth excitation force.

[0021] The stamping sheet 5 is made of silicon steel. The silicon steel stamping sheets 5 are stacked to form an arc-shaped air magnetic bridge 6, which not only blocks magnetic leakage but also stabilizes the main magnetic circuit with high magnetic permeability and low loss characteristics, and synergistically suppresses eddy current excitation and high frequency vibration.

[0022] The thickness of the stamped sheet 5 is 0.5mm. The 0.5mm silicon steel stamped sheet 5 is stacked with an arc-shaped air magnetic bridge 6, which further reduces eddy current loss and hysteresis noise on the basis of refining the magnetic circuit distribution, and suppresses high-frequency electromagnetic excitation through dual paths.

[0023] The rotating shaft 1 is fixed in the inner hole of the rotor core 4 by a heat fitting. The heat fitting achieves an interference fit between the rotating shaft 1 and the rotor core 4, ensuring the rotor structure's anti-centrifugal rigidity under high-speed rotation, while maintaining the integrity of the inner circular magnetic circuit and electromagnetic symmetry.

[0024] The specific embodiments of this utility model disclosed above are merely illustrative of the present utility model. These specific embodiments do not exhaustively describe all details, nor do they limit the utility model to only the described embodiments. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of this utility model, thereby enabling those skilled in the art to better understand and utilize it.

Claims

1. A rotor structure for reducing electromagnetic excitation force of a permanent magnet motor, comprising a shaft (1), an end plate (2), a permanent magnet (3), and a rotor core (4), wherein the rotor core (4) is formed by stacking multiple stamped laminations (5), the multiple stamped laminations (5) forming multiple lamination slots evenly distributed along the circumferential direction, the permanent magnet (3) being embedded in the lamination slots, the shaft (1) being installed in the inner hole of the rotor core (4), and the end plate (2) being located at both axial ends of the rotor core (4), characterized in that: The stamping sheet (5) is provided with an air magnetic bridge (6), which extends along the outer circle of the stamping sheet (5), and the extension shape of the air magnetic bridge (6) matches the outer circle curvature of the stamping sheet (5).

2. The rotor structure for reducing electromagnetic excitation force of a permanent magnet motor according to claim 1, characterized in that: The permanent magnet (3) has a cuboid structure.

3. The rotor structure for reducing electromagnetic excitation force of a permanent magnet motor according to claim 1, characterized in that: The permanent magnets (3) are arranged in a V-shape.

4. The rotor structure for reducing electromagnetic excitation force of a permanent magnet motor according to claim 1, characterized in that: The stamping sheet (5) is made of silicon steel.

5. The rotor structure for reducing electromagnetic excitation force of a permanent magnet motor according to claim 1, characterized in that: The thickness of the stamped sheet (5) is 0.5 mm.

6. The rotor structure for reducing electromagnetic excitation force of a permanent magnet motor according to claim 1, characterized in that: The rotating shaft (1) is fixed in the inner hole of the rotor core (4) by a heat-shrink method.

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