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Due to coupling of in-wheel motor and wheel/tire, the electric wheel system of in-wheel motor driven vehicle is different from tire suspension system of internal combustion engine vehicle both in the excitation source and structural dynamics. Therefore emerging dynamic issues of electric wheel arouse attention. Longitudinal vibration problem of electric wheel system in starting condition is studied in this paper. Vector control system of permanent magnet synchronous hub motor considering dead-time effect of the inverter is primarily built. Then coupled longitudinal-torsional vibration model of electric wheel system is established based on rigid ring model and dynamic tire/road interface. Inherent characteristics of this model are further analyzed. The vibration responses of electric wheel system are simulated by combining electromagnetic torque and the vibration model. The results indicate that abrupt changes of driving torque will cause transient vibration of electric wheel system.

The motor has vibration characteristics of order and multi-band in the frequency domain, which is different from the internal combustion engine when it is used as the vehicle’s drive. These characteristics cannot be briefly attenuated by general methods, but make the phononic crystal (PC) an ideal solution to eliminate the vibration transmission of the motor, because the concentrated vibration peak can easily be blocked by the bandgap. In this paper, one dimensional locally resonant phononic crystal (LRPC) which has low-frequency bandgaps are arranged on the automotive subframe to absorbing vibration. The partial coherence analysis is used to analyze the transfer characteristic of vibration on the subframe. Then, 6 main paths are selected from the 18 vibration transmission paths, based on its high ratio of partial coherence coefficient in a certain frequency, and the arranged position, the spring stiffness and the resonator’s mass of the LRPCs are chosen based on this result.

Compared with the low-frequency ignition order of mechanical and combustion noise of an internal combustion engine, the noise of electric drive assembly of electric vehicles is mainly the high-frequency whining noise generated by electromagnetic forces of motors and gear meshing of reducers, as well as the high-frequency umbrella-shape noise generated by DC/AC pulse width modulation. Although the radiated sound power of these high frequency noise is far less than that of an internal combustion engine, the high frequency noise of the motor and the reducer is subjectively quite annoying. This paper studies the characteristics of electromagnetic noise of a permanent magnet synchronous motor in an electric car. By testing and analyzing of noise sources of an electric motor in the car and on a test rig, the spatial order characteristics and amplitude-frequency characteristics of the electromagnetic forces are revealed. The noise orders are multiples of the number of motor poles.