Analysis On Mechanical Modeling And Vibration Characteristics Of Permanent Magnet Multi-degree-of-Freedom Motor

Motors have attracted worldwide attention,with the advantages of high efficiency,energy saving and high accuracy.In order to adapt to the development of modernization and reduce the noise of motors,motors are no longer connected with traditional mechanical transmission devices,but directly connected with loads or working machines.In this paper,a new type of multi-degree-of-freedom permanent magnet synchronous motor(PMSM)is studied.The damping liquid is filled between the stator and the rotor to suspend the rotor in the stator shell,and the stator coil drives the suspension and motion of the rotor to reduce the friction loss of the motor.However,when the rated speed of the new kind of motor approaches the critical speed,it may cause multiple resonances of the motor,leading to eccentricity and stall of the rotor.Therefore,the study of vibration characteristics and rotor dynamics of multi-degree-of-freedom motors can effectively predict the impact of stress and deformation caused by vibration on the stable operation of motors.In this paper,the modal and dynamics of the motor are analyzed and the specific research contents are as follows:Firstly,the background and significance of multi-degree-of-freedom motors are introduced.The structure characteristics of liquid suspension multi-degree-of-freedom motors are understood,and the research status of this kind of motors at home and abroad is described.The research method and application of driving strategy and modal analysis of the motor are formulated.The basic structure size of motor is defined clearly,and the three-dimensional mathematical model of the motor is established by COMSOL software.The electromagnetic field and force distribution of the spherical motor are simulated and analyzed by finite element software.The analytical method is also used to solve the magnetic field,which are compared with the result of FEM.Secondly,according to the magnetism and solid coupling Vibration theory,the stress of stator core are analyzed and studied under the condition of coil electrification,and the deformation displacement and stress-deformation distribution of the core are calculated.The prestressing analysis of the stator spherical shell of the motor is carried out.The deformation and displacement distribution of the first three modes are calculated and compared with the force wave distribution.The vibration data of spherical shells are collected by using vibration displacement sensors,and the results are compared with those of finite element simulation.Since the radial electromagnetic force is the main factor affecting the normal operation of the motor,the modal analysis of the electrified motor is carried out after electrified.Finally,the dynamic analysis of the spherical motor rotor is carried out,and the modal changes of the rotor under different states are compared and analyzed by using the dynamic characteristics of the rotor system.Then the change of critical speed of rotor under different stiffness conditions is analyzed,and the gyroscopic effect of motor is predicted and analyzed.The experimental platform was built to fill different liquids between stator and rotor spherical shells.An experimental analysis of the deformation displacement on the stator shell at different liquid velocities is carried out.The work has a certain reference value for the optimization design of the motor,which laid a theoretical foundation for the further optimization of the motor.