Dynamical Modeling Of Coupled Mechanical,Electric And Magnetic Fields Of Electric Vehicle Electric Drive System And Vibration Characteristics Research

Electric drive system is a typical complex mechanical electrical magnetic multi field coupling system that includes drive motors,transmission mechanisms,and other components.It can be divided into mechanical systems,electrical systems,and air gap magnetic fields that connect the two.The multi field coupling effect makes the electric drive system exhibit very complex dynamic characteristics,and the various vibration frequencies of the motor and mechanical system overlap with each other,which brings many difficulties to the vibration source location and vibration reduction control of the system.With the development of electric drive systems towards high rotational speeds,high dynamics,and integration,the mechanical vibration problems caused by the coupling of mechanical,electrical,and magnetic fields have become more complex and prominent,especially under electromagnetic excitation such as motor electromagnetic torque,unbalanced magnetic pull,and electromagnetic stiffness,under dynamic excitation inside the gearbox such as transmission error,time-varying meshing stiffness,backlash and under transient load excitation caused by unstable operating conditions,the reliability and dynamic response characteristics of the electric drive system are seriously deteriorated.This paper takes the electric drive system of an electric vehicle as the research object,and establishes an electromagnetic multi-field coupling dynamic model of the interior permanent magnet synchronous motor(IPMSM),which includes the structure of the motor,nonlinear magnetic field characteristics,and relative motion of stator and rotor.It analyzes the nonlinear electromagnetic response of IPMSM and the excitation characteristics of rotor eccentricity.Finally,considering the nonlinear characteristics of the drive motor and the meshing excitation of the gear pair,a multi field coupling dynamic model of the electric drive system is established to reveal the vibration characteristics of the electric drive system under multi source excitation.The main research contents of this article are as follows:(1)Electromagnetic coupling model of permanent magnet synchronous motor.A magnetic field analytical method for dual V type permanent magnet synchronous motors is proposed based on the equivalent magnetic network method.The potential magnetic flux paths of the stator and rotor are modeled using modular permeability elements to take into account structural factors such as stator slot,magnetic pole distribution,and leakage flux.The nonlinear saturation state of the magnetic field is calculated using an iterative method.Finally,by superposing winding excitation in the same sub coordinate system,an electromagnetic coupling model is established with the input of winding phase current and motor rotor displacement.The distribution of the coupling magnetic field and the nonlinear characteristics of ferromagnetic materials are verified and analyzed through finite element software.(2)Mechanical-electrical-magnetic multifield coupling dynamic model of permanent magnet synchronous motor.Combined with the cross-grid magnetoconductivity element with modeling flexibility and the fixed-grid motion modeling method with variable magnetoconductivity parameters,an improved air-gap motion modeling method is proposed,which not only improves the dynamic analysis efficiency but also has significant accuracy advantages in dealing with the overlapping of motion elements.On this basis,based on electromagnetic theory,the potential relationship between the electromagnetic torque and unbalanced magnetic pull response of permanent magnet synchronous motor and the coupled magnetic field is established,and the dynamic model of mechanic-electrical-magnetic multifield coupling of permanent magnet synchronous motor is obtained after correlation with the electromagnetic coupling model.Based on the vector control method,the permanent magnet synchronous motor is simulated and analyzed,and the cross-coupling influence law of the stator and rotor magnetic field,the nonlinear response characteristics of the motor,the eccentric excitation characteristics of the rotor and the eccentric detection method based on branch current are studied.(3)Multi-field coupling dynamic model and characteristic analysis of electric drive system.Based on the slice method and potential energy method,the relationship between gear meshing stiffness and meshing angle displacement is obtained.Comprehensively considering nonlinear factors such as time-varying meshing stiffness,meshing error,and gear center displacement,a gear transmission dynamics model with concentrated parameters is established.On this basis,a multi-field coupling dynamic model of the electric drive system is established,and the influence of stiffness excitation,static meshing error and electromagnetic torque disturbance on the nonlinear vibration characteristics of the electric drive system is simulated and analyzed.(4)Study on multi-field coupling vibration characteristics of electric drive system under complex working conditions.The cross-coupling dynamics of mechanical vibration and electromagnetic field excitation of electric drive system under the combined action of external load,speed and load impact,internal dynamic excitation of gear transmission system,and electromagnetic excitation of drive motor were studied,and the sensitivity of vibration information of the electric drive system to be monitored remotely by stator current under different working conditions was simulated and analyzed,and the multi-field coupling vibration mechanism of electric drive machine-electromagnetism was revealed.