Electromagnetic Vibration And Noise Characteristics And Its Suppression Of Permanent Magnet Synchronous Motor Used For Electric Vehicles

Electric vehicles(EVs)are gradually replacing traditional fuel vehicles due to their natural advantages of low cost,easy maintenance,high energy utilization efficiency,low environmental pollution,and are widely used.As a key component,the performance of the driving motor directly determines the power and competitiveness of EVs.Interior permanent magnet synchronous motor(IPMSM)has become the best choice for EVs driving due to its high efficiency,small size,high power density and wide speed range.While focusing on the electromagnetic(EM)performance,the EM vibration and noise performance of IPMSM also determines the passenger comfort and operational reliability of EVs.Therefore,theoretical analysis,numerical simulation,and multi-field coupling optimization of IPMSM’s EM vibration noise performance are of great engineering value and practical significance.This dissertation takes IPMSM as the research object and focuses on the key scientific issues such as EM-structural-acoustic field distributions,EM vibration noise characteristics and multi-physics coupling optimization of IPMSM.Then a series of research such as IPMSM magnetic equivalent circuit(MEC)analytical calculation,stator structural equivalent network model,EM-structural-harmonic-acoustic multi-physics field coupling theoretical analysis and 3D numerical simulation,vibration noise multiphysics field coupling optimization method,and the influence of inverter on motor vibration and noise are carried out in depth.The main contents include:Firstly,the MEC model of IPMSM with the effects of magnetic circuit saturation,rotor salient pole and stator slotting is developed to analyze the spatial and temporal distribution of air-gap EM field and EM force,and to reveal the influencing factors of airgap EM force,which also provides an effective theoretical tool for IPMSM performance optimization-design.The effects of magnetic circuit saturation,rotor salient pole and stator slotting on air gap magnetic field and magnetic permeability distribution are separated,the analytical expressions of air gap EM force and EM torque of IPMSM are derived,and the distribution characteristics of air gap magnetic field and EM force wave under different operating conditions and different dq axis armature currents of IPMSM are analyzed.The sampling and modulation effects of the stator teeth on the air gap EM force are further investigated.Based on the MEC model,the distribution characteristics,influencing factors and causes of air-gap EM force harmonics are analyzed.Then,the transfer function models of the air-gap EM force and the stator tooth force are proposed.Secondly,the improved hollow cylindrical shell theory and the equivalent structural network(ESN)model of the stator assembly are proposed to reveal the natural modal distribution and forced vibration characteristics of the motor stator assembly system,to make up for the deficiencies of existing research in the EM vibration and noise theoretical analysis and to lay the foundation for the analytical calculation of IPMSM EM vibration and noise performance.Based on the analysis of the multi-degree-of-freedom structural system and the forced harmonic vibration characteristics of the cylindrical shell,the ESN model of the stator assembly system is proposed,and the vibration structure transfer functions,natural frequencies,and physical quantities of displacement,velocity and acceleration of the stator assembly system corresponding to each order of modal in the circumferential direction are derived to reveal the influence of the structural parameters and the damping ratio on the vibration transfer functions of the stator assembly system.Then the distribution characteristics of physical quantities such as sound field radiated power and sound pressure level of IPMSM are further investigated.Finally,the verification is carried out by modal knocking tests.Thirdly,this dissertation proposes an EM-structural-harmonic-acoustic multiphysics field coupling analytical calculation method of IPMSM to analyze the EM vibration and noise characteristics of IPMSM under full working conditions,and provides an analytical method for IPMSM parameter design,vibration and noise analysis and suppression.Firstly,an IPMSM EM-structure-harmonic-acoustic multi-physics field coupling analytical calculation model is established by combining IPMSM MEC and ESN model,and the EM vibration noise characteristics of IPMSM in no-load and on-load operating conditions are calculated.Then,the coupled 3D multi-physics field(EMstructural-harmonic-acoustic)numerical calculation approach for IPMSM is proposed to analyze the distribution characteristics of IPMSM air gap EM field(EM force,EM efficiency,etc.),structural field(modal pattern,vibration velocity)and acoustic field(equivalent radiated power,sound pressure level).And the difference between the analytical and 3D numerical model in the vibration noise calculation of is elaborated.Finally,the accuracy of the analytical model is verified through the bench test.Fourthly,the EM-structural-harmonic-acoustic multi-physical field and multiobjective optimization method of IPMSM is proposed to carry out multi-field and multiobjective optimization of the EM and vibration noise performance of the motor,enriching the research of IPMSM electromagnetic vibration noise suppression and multi-field performance optimization methods.Based on the multi-physics field analytical model,the effects of different pole-slot fits,topologies and dimensional parameters on the EM vibration noise performance of IPMSM are compared and analyzed to reveal the dual influence characteristics of structural dimensions on the EM vibration noise performance of IPMSM.then the sensitivity and correlation relationships between optimization objectives and variables in the optimization process are obtained by sensitivity analysis methods.Combining modern particle swarm optimization algorithm and IPMSM EM vibration noise analytical calculation method,the IPMSM is optimized with structural parameters as optimization variables,EM output torque,vibration velocity and effective material price as optimization objectives,and the performance of IPMSM before and after optimization are compared.Finally,based on the optimized IPMSM structure parameters,the prototype is fabricated and the related experimental verification is carried out.Finally,this dissertation proposes the IPMSM carrier vibration noise calculation and suppression control strategy considering the time harmonics introduced by the inverter,reveals the influence law of the inverter and control strategy on the IPMSM EM vibration noise,and provides a reference for the research of optimal control strategy of IPMSM EM vibration noise.Based on the analytical calculation method of IPMSM EM vibration noise and the field-circuit coupling FEM model,the distribution characteristics of armature current carrier harmonics and EM force carrier harmonics considering the influence of inverter and control strategy are studied,and the characteristics of IPMSM carrier vibration noise caused by inverter are further analyzed.Then,the influence of inverter carrier ratio on IPMSM current carrier harmonics and EM force carrier harmonics is investigated.On this basis,the suppression effect of adjusting the carrier frequency of the inverter on the IPMSM carrier vibration noise characteristics is studied,and the optimal control strategy to weaken the IPMSM carrier vibration noise caused by the inverter is proposed.