Numerical and experimental investigations on the vibration behavior of a high-speed planetary gearbox

Abstract

Increasing the speed of the electric motor can significantly improve the power density of the powertrain of EVs (Electric Vehicles), resulting in a smaller size and thus weight and cost advantages. Achieving acceptable NVH behavior becomes more difficult at higher speeds, partly because the excitation frequencies of the gears cover a wider frequency range and therefore higher natural frequencies can also be directly excited. In the Speed4E joint research project, a high-speed electromechanical powertrain was developed, manufactured, and tested to investigate the main challenges on the NVH- and efficiency-behavior of high-speed powertrains. The high-speed design of the Speed4E drivetrain results in maximum electric motor speeds of up to 50,000 rpm, combined with a torque of up to 45 Nm at the transmission input shafts. This study presents the experimental results on the vibration behavior of the high-speed planetary gearbox, a comparison with the corresponding results of a highly efficient calculation method of the gearbox vibration excitation, and the theoretical background of the calculation method is presented. The results indicate the potential to improve the vibration behavior of high-speed drives in EVs and provide a deep understanding of the challenges associated with high speeds.