This paper presents a method based on the finite element simulation, the electromagnetic field, electromagnetic force, electromagnetic vibration and electromagnetic noise characteristics of a double-rotor permanent magnet synchronous in-wheel motor under multiple operating conditions are systematically studied. On the integration of previous methods, a program of multi-physics modeling and analysis of electromagnetic vibration and noise of motor is set up. Firstly, a new electromagnetic structure design of double-rotor permanent magnet synchronous in-wheel motor is proposed. Based on Maxwell stress equation, the analytical model of the radial electromagnetic force of the motor is established. The spatial domain, time domain and frequency domain analysis of the internal and external electromagnetic force and torque ripple of the double-rotor permanent magnet synchronous in-wheel motor are carried out by means of finite element simulation. Analysis shows that the radial electromagnetic force before the 5th order is mainly influential, tangential electromagnetic force before the 4th order is mainly influential.

With the increasing of order, the amplitude is gradually reduced. The amplitude of the first order is the highest. According to the different modeling methods of stator windings, four finite element models in 3D structural field are designed for the double-rotor permanent magnet synchronous in-wheel motor. Then, the effects of quality and stiffness of the effective length and end of stator windings on the stator modal frequency are summarized and compared. The results show that the effect of winding mass and stiffness on the overall modal frequency of the stator is nearly canceled. After that, the 3D structural field model of the double-rotor permanent magnet synchronous in-wheel motor is used to simulate the transient dynamics under radial concentrated force loading. Based on the simulation results, the inner and outer lateral deformation of stator is analyzed in time domain and frequency domain.

Finally, the harmonic response analysis of 3D structural field model of the double-rotor permanent magnet synchronous in-wheel motor is proposed, and the 3D sound field boundary element model of electromagnetic noise is established. The acoustic boundary element analysis under multiple operating conditions is carried out, including sound pressure analysis of stator surface, sound pressure analysis of field point and analysis of sound pressure frequency response characteristics at different field points. The results show that the electromagnetic noise of motor is more sensitive to the high frequency excitation, and the sensitivity of the electromagnetic noise in the radial position is significantly larger than that of the axial position. The analysis process proposed in this paper can provide support for the prediction, optimization and analysis of influencing factors of electromagnetic vibration and noise during the period of motor design.

Prof. Dr.-Ing. Lijun Zhang, Tongji University, CHINA; Mr. Jie Xu, Tongji Univeristy, CHINA; Dr.-Ing. Dejian Meng, Tongji Univeristy, CHINA