New teeth surface and back (TSB) modification method for transient torsional vibration suppression of planetary gear powertrain for an electric vehicle

Abstract

Advantages of planetary gear powertrain (PGT) for electric vehicles (EVs) are the high degree of efficiency, various reduction ratio, stress distribution by the planet gear and compaction in designing driving system. However there is noise in running at high rotational speed, so the transient torsional vibration suppression of the PGT for EVs become extremely essential and urgent. This study presents a 4 + N degree of freedom (DOF) nonlinear torsional system that essentially describes a PGT of EVs example, and further study on influence of novel TSB modification on transient vibration of planetary gear powertrain for an electric vehicle. In particular, the vibration of the PGT during the speed-up process, as excited by dynamic torque of motor generator (MG), time-varying mesh stiffness of front and back gear teeth, and also teeth backlashes, are investigated using a nonlinear torsional transient model. Then a full PGT model during the speed-up process is proposed and numerically solved to obtain the transient vibration acceleration. Dynamic response results of the PGT are also successfully compared and analyzed under different teeth backlashes. Finally, an improved genetic algorithm is applied to construct optimal relationship between the transient vibration and the TSB modification, and further the optimum three-dimensional TSB modification of sun-gear is finally obtained. The simulation and experiment results indicated that the proposed novel TSB modification method effectively suppressed the PGT transient vibration and vehicle jerk, at the same time, improved the ride comfort during the high-speed driving mode.