Study On Electromechanical Coupling Dynamic Performance Of Axial-radial Magnetic Field Compound Motor Used For Direct Drive In Wheel

The direct drive technology of the hub motor has the advantages of shortening the transmission chain,simplifying the automobile structure and improving the transmission efficiency.It is an important development direction of electric vehicle technology.In order to solve insufficient power of wheel hub motors,the project develops an axial-radial magnetic field compound PMSM.However,its complicated thin-walled outer rotor structure and harsh automotive conditions will adversely affect dynamic performance.Considering the influence of electromagnetic and structural parameters on dynamic performance,study on electromechanical coupling dynamic performance of compound motor will be conducted.The main work is as follows:(1)Based on the configuration of the integrated electric wheel,the basic dimensions of the axial-radial magnetic field compound motor are determined.ANSYS finite element software is selected to discuss multiphysics modeling and simulation methods.The load transfer coupling method is used to realize the electromechanical coupling of the multiphysics model.The electromagnetic excitation force caused by the rotor motion is not conducive to loading.According to the principle of force balance,the reversal method is used to turn the rotor into a static structure.Then,electromagnetic transient and steady simulations are conducted to verify the rationality of the multiphysics model.(2)Based on Maxwell tensor method,electromagnetic force is calculated from air gap magnetic field.Through Fourier decomposition,the spatiotemporal characteristics of electromagnetic excitation force are obtained.Based on the multiphysics model,the outer rotor mode is solved.It provides a basis for dynamic performance evaluation.The load transfer coupling is realized by the distributed force method.Based on the modal superposition method,the dynamic response of the outer rotor surface is calculated.Therefore,the electromechanical coupling dynamic performance of the outer rotor is analyzed.Electromagnetic structural parameters of the outer rotor affect the electromechanical coupling dynamic performance of the rotor.The influence of the rotor core thickness and the permanent magnet pole arc coefficient on the rotor dynamic performance is discussed.(3)Manufacturing and assembly errors have an important influence on the electromagnetic and dynamic characteristics.Different eccentric forms of the compound motor are discussed and eccentric models are established.Spatiotemporal characteristics of air gap magnetic field and electromagnetic force caused by eccentricity are simulated and analyzed.The effects of different eccentric forms and eccentricity on the rotor dynamic performance are discussed.The electromechanical coupling dynamic performance of compound motor is systematically studied in this thesis.Based on the electromagnetic-structure multiphysics model,the effects of electromagnetic structure parameters and eccentricity parameters on the rotor dynamic performance are discussed.This study provides a theoretical basis and method for the design of the dynamic performance of compound external rotor motor.