CN-121997678-A - High-precision modal analysis method for motor assembly

Abstract

The invention discloses a high-precision modal analysis method of a motor assembly, which comprises the following steps of 1, establishing a finite element model of the motor assembly, defining transverse isotropic material properties for a silicon steel sheet laminated structure in the motor assembly, 2, defining a nonlinear connection relation in the finite element model based on an actual assembly relation of the motor assembly, 3, carrying out nonlinear statics analysis on the finite element model to obtain global rigidity distribution of the motor assembly in a specific assembly state, and systematically solving the problem of insufficient simulation precision caused by neglecting silicon steel sheet laminated anisotropy and assembly contact nonlinearity in the traditional method, thereby remarkably improving the prediction accuracy of the inherent frequency and modal vibration mode of the motor assembly, providing a reliable basis for structural resonance avoidance and optimization design, simultaneously reducing the dependence on physical tests, and improving the research and development efficiency.

Inventors

• XU MENGNA
• ZHOU BIN
• CAO GUANHUI

Assignees

• 浙江奥思伟尔电动科技有限公司

Dates

Publication Date

20260508

Application Date

20260409

Claims (10)

1. 1. The high-precision modal analysis method for the motor assembly is characterized by comprising the following steps of: step 1, establishing a finite element model of a motor assembly, and defining transverse isotropy material properties for a silicon steel sheet laminated structure in the motor assembly; Step 2, defining a nonlinear connection relation in the finite element model based on the actual assembly relation of the motor assembly; Step 3, nonlinear statics analysis is carried out on the finite element model so as to obtain global rigidity distribution of the motor assembly in a specific assembly state; And 4, taking the global rigidity distribution as an input condition, and carrying out dynamic modal analysis on the motor assembly so as to obtain the natural frequency and the modal shape under the rigidity distribution state.
2. 2. The method of claim 1, wherein in step 1, establishing a finite element model of the motor assembly comprises: geometrically simplifying the stator winding to remove tiny features; and carrying out equivalent modeling on the silicon steel sheet laminated structure of the stator core and the rotor core.
3. 3. The method according to claim 2, wherein in the step 1, the definition of the transverse isotropic material property is based on a preset global coordinate system, the global coordinate system uses a rotation center of the motor rotating member as an origin, a rotation plane as an X-Y plane, and a motor axial direction as a Z axis.
4. 4. The method of claim 3, wherein the parameters required for defining the transverse isotropic material properties include silicon steel sheet density (ρ), X-direction elastic modulus (E X ), Y-direction elastic modulus (E Y ), Z-direction elastic modulus (E Z ), XY plane Poisson's ratio (v X-Y ), XZ plane Poisson's ratio (v X-Z ), YZ plane Poisson's ratio (v Y-Z ), XY plane shear modulus (G X-Y ), XZ plane shear modulus (G X-Z ), YZ plane shear modulus (G Y-Z ), wherein E X =E Y ,ν X-Z =ν Y-Z ,G X-Z = G Y-Z , 。
5. 5. The method according to claim 1, wherein in the step 2, the nonlinear connection relationship includes friction contact between the motor housing and the stator core, friction contact between the rotating shaft and the rotor sheet, and interference is set according to actual assembly.
6. 6. The method according to claim 5, wherein in the step 2, the contact control of the nonlinear connection relationship adopts a multi-point constraint algorithm, and a spring unit is arranged at the motor bearing position to equivalent the rigidity of the bearing.
7. 7. The method according to claim 1, wherein in the step 3, the nonlinear statics analysis is used for calculating the distribution of contact stress and friction stress of the motor assembly under the pre-tightening force.
8. 8. The method according to claim 7, wherein in the step 3, the specific assembling state is a peak moment, a trough moment or a final stable moment of the stress state in the nonlinear statics analysis process.
9. 9. The method for high-precision modal analysis of motor assembly according to claim 8, wherein in step 1, a second-order hexahedral unit is used for meshing of stator core, stator winding, rotor core, permanent magnet, balance plate and rotor compression ring, and a second-order tetrahedral unit is used for motor housing, end cover and motor shaft.
10. 10. The method according to claim 1, wherein in the step 4, the dynamic modal analysis is a constraint modal analysis, and the constraint modal analysis is used for obtaining the resonance frequency and the vibration mode of the motor assembly.

Description

High-precision modal analysis method for motor assembly Technical Field The invention relates to the technical field of motors, in particular to a high-precision modal analysis method for a motor assembly. Background Modal analysis is the basis of structural dynamics analysis, and provides the most basic structural inherent characteristics, namely inherent frequency and vibration mode, for a plurality of subsequent dynamics analysis types. The essence of modal analysis is the process of solving the special solution of the kinetic second differential equation (formula) i.e.. The method is essentially a linear analysis, the type of connection relationship inside the system defaults to be fixed or not separated, and stiffness calculation is carried out through penalty functions in the normal direction and the tangential direction of the contact surface respectively. Even if a nonlinear model is arranged on the material module, and nonlinear contact is arranged on the contact module, linear analysis can be carried out according to the model state equivalent to the initial moment in the actual analysis process, and the numerical simulation process ignores the nonlinear influence existing objectively. Friction contact is a typical nonlinear contact, and in the process of friction effect, the change of friction force directly affects the system contact stiffness, so that the natural frequency of the structure is greatly changed. In addition, since the stator core and the rotor core of the motor are both of silicon steel sheet laminated structures, the material properties of the axial direction and the cross section of the stator core and the rotor core cannot be consistent (elastic modulus, poisson ratio and shear modulus) and are difficult to obtain through simple material tests, the current practical method is to perform a force hammer impact test on an iron core test piece, scale the material properties of the silicon steel sheet laminated structures based on test results, determine the most suitable parameters, and then perform subsequent simulation analysis, so that the mode has long iteration period and high cost consumption. Therefore, a series of equivalent processing modes exist in the industry, such as modeling analysis is conducted on a silicon steel sheet laminated structure, all contacts in a motor system are regarded as linear fixed connection, global common node sharing topology is set, a stator iron core, a winding, a rotor iron core and a permanent magnet are equivalent to different degrees, partial entities are restrained from conducting grid modeling, simulation is conducted through establishing coupling points with mass, gravity center and moment of inertia properties, and the like, and the simplified mode has reference value on modal vibration modes and modal frequencies on cross sections, but larger errors of axial modal frequencies are ignored. In view of the foregoing, a high-precision modal analysis method for a motor assembly is needed to solve the drawbacks of the prior art. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a high-precision modal analysis method for a motor assembly, and aims to solve the problems. The application provides a high-precision modal analysis method of a motor assembly, which comprises the following steps: step 1, establishing a finite element model of a motor assembly, and defining transverse isotropy material properties for a silicon steel sheet laminated structure in the motor assembly; Step 2, defining a nonlinear connection relation in the finite element model based on the actual assembly relation of the motor assembly; Step 3, nonlinear statics analysis is carried out on the finite element model so as to obtain global rigidity distribution of the motor assembly in a specific assembly state; And 4, taking the global rigidity distribution as an input condition, and carrying out dynamic modal analysis on the motor assembly so as to obtain the natural frequency and the modal shape under the rigidity distribution state. The method has the advantages that the nonlinear connection relation is defined through the integrated transverse isotropic material, the overall rigidity distribution of nonlinear statics analysis is innovatively transferred to modal analysis, the problem of insufficient simulation precision caused by neglecting the lamination anisotropy of the silicon steel sheets and the nonlinearity of assembly contact in the traditional method is systematically solved, the prediction accuracy of the inherent frequency and the modal vibration mode of the motor assembly is remarkably improved, reliable basis is provided for structure resonance avoidance and optimization design, dependence on physical tests is reduced, and research and development efficiency is improved. Further, in the step 1, establishing a finite element model of the motor assembly includes: geometrically simplifying the stator winding to remove tiny