Torque Ripple Modeling And Experiment Of In-wheel Motor

The in-wheel motor drive mode has become an important direction for the development of electric vehicles due to its distinctive structural characteristics and outstanding performance advantages.The in-wheel motor has become a hot spot in academic research.In the in-wheel motor drive mode,the motor is directly connected to the wheel,The torque fluctuation of the motor will directly affect the vibration characteristics and grounding performance of the tire,thereby affecting the performance of the whole vehicle.This article focuses on the in-wheel motor drive mode in distributed drive electric vehicles,and studies the fluctuation characteristics of the output torque of the in-wheel motor and the coupling characteristics of the motor torque fluctuation and the tire.Firstly,the influence mechanism of the torque fluctuation caused by the permanent magnet synchronous motor cogging torque and rotor magnetic field harmonics are analyzed.Based on the JMAG finite element analysis software,a finite element model of a permanent magnet synchronous motor is established that takes into account the influence factors of torque fluctuations such as cogging torque,air gap magnetic field harmonics,and magnetic circuit saturation,and through the JMAG-RT toolbox to convert the finite element model into a real-time motor model.Secondly,the mechanism of motor torque fluctuation caused by factors such as SVPWM algorithm,inverter,current sensor and rotor position sensor are analyzed.Based on Simulink,the motor vector control algorithm model,SVPWM algorithm model,current sensor error model and rotor position sensor error model are built,Then the Simulink control algorithm model and the real-time motor model are jointly simulated.Then,according to the direct dynamic measurement method of motor torque fluctuation,a torque fluctuation test system of the in-wheel motor was built.Based on the Labview-RT real-time environment,the experimental test data was collected and processed with Labview software.And the experimental results were observed and analyzed.Finally,the tire structure is discretized,and then the internal structural force of the tire and the contact force of the tread are solved,and the dynamic equations of the rim and mass points are established to model the high-frequency dynamic model of the tire.The motor torque fluctuation model and the tire model are jointly simulated to analyze the coupling characteristics of the motor and the tire.The results show that the motor torque fluctuation will affect the longitudinal force and slip rate of the tire,but has little influence on the vertical force.