Torsional Vibration Control For Driveline Of A Electric Car Based On Motor Torque Ripple Suppression

Nowadays,Electric vehicles are the main types of new energy vehicles.Compared with traditional internal combustion vehicles,the powertrain of electric vehicles have large variations in the power source and structure.As the result,there are new features in the torsional vibration of the driveline.Studying how to reduce the torsional vibration of electric vehicle's(EV)powertrain is of great significance to improve the safety and comfort of the whole vehicle.The driving motor is the main excitation source for the steady-state torsional vibration of the driveline.The magnitude of the torque fluctuation directly affects the steady-state torsional vibration response of the powertrain.The purpose of this paper is to reduce the steady-state torsional vibration of the driveline from the viewpoint of motor torque ripple suppression.In order to achieve this goal,the torque fluctuation characteristic of permanent magnet synchronous motor(PMSM)is firstly analyzed.Sources of divergence from ideal conditions in both the motor and associated power converter in PMSM motor drives are the main source of torque ripple.An analytical model of torque ripple is deduced and established.With the simulation result of electromagnetic software JMAG Designer,the motor design and structure contribution to torque ripple is in a low level.To suppress torque ripple of permanent magnet synchronous motor,based on the relationship of current and torque ripple,it is proposed to reduce motor torque ripple by suppressing harmonic current.To suppress the harmonic current,a real-time online algorithm for extracting current harmonic amplitude is proposed to suppress the harmonic current,and the PI controller is used to suppress it after extracting the harmonic current.By suppressing the harmonic current,the motor torque ripple is eventually suppressed.The parameter of PI controller is analysed in detail.Based on the MATLAB/Simulink platform,the simulation model of of PMSM' torque ripple suppression was built to verify the effectiveness of the strategy.Simulation result shows that the 6th or 12th harmonic current PI controller can greatly reduce the ampltude of 6th or 12th harmonic torque,which confirm the effectiveness of the strategy.This algorithm is more flexible and adaptable,without involving any additional hardware and off-line experimental measurement.Subsequently,the effect of motor torque ripple suppression on the reduction of the steady-state torsional vibration of the drive train was analyzed.A 5-DOF linear discrete analytical torsional vibration of the powertrain of a electric car was established.The natural frequency character was then analyzed.Focusing on the effect of motor torque ripple suppression strategy on reducing torsional vibration response under steady-state conditions of the vehicle,the torsional vibration simulation model established by MATLAB/Simulink was used to verify the improvement of steady-state torsional vibration.The vibration response of four driving conditions of EVs was discussed in detail.The simulation results show that with the motor torque ripple suppression strategy proposed in this paper,the amplitude of the primary frequency component in the steady-state torsional vibration response can be greatly reduced,and the damping effect is guaranteed.