Analysis and Suppression of Longitudinal Vibration of Electric Wheel System Considering Rotor Position Error

Electric wheel system (EWS) has become a research hotspot of the electric vehicle. As motor torque is directly exerted on wheels, torque ripples could induce longitudinal vibration that is more noticeable than traditional vehicles. In this article, the influence of rotor position error on the longitudinal vibration of the EWS is analyzed and suppressed. First, a bench test of EWS is conducted to observe the characteristics of the longitudinal vibration and harmonic components in the phase current. Then, by constructing an analytical model, the influence of rotor position error on the phase current and torque ripple is discussed. Moreover, with a dynamic model of the EWS, the longitudinal vibration considering the rotor position error is deduced. As the analytical and experimental results are consistent, the accuracy of the models is proven, and the relationship between rotor position error and longitudinal vibration of the EWS is clarified. Finally, to attenuate the longitudinal vibration related to rotor position error, an observer based on the extended Kalman filter is designed to replace the variable reluctance resolver for rotor positioning. The simulation result verifies the feasibility of the observer as well as its effectiveness in longitudinal vibration control.