Vibration Analysis of Series-parallel Hybrid Powertrain System under Typical Working Condition and Modes

Powertrain system of series-parallel hybrid vehicle contains multiple excitation sources like engine, motor and generator. The reduction of noise and vibration is quite difficult during multiplex working modes or the switch of modes. Aiming at Series-parallel hybrid powertrain system which contains engine, motor and planetary gear subsystems, this paper considered a typical working condition which is based on the power control strategy and established the torsional vibration mechanical model of hybrid powertrain system. The inherent characteristics and transient vibration response of the electric mode, hybrid mode and parking charging mode were studied and it was discovered that the repetitive frequency of the powertrain system under the three working modes is the same which is only related to inertia and meshing stiffness of planetary gear system. The non-repetitive frequency and corresponding vibration modes under the electric mode and parking charging mode are both close. The transient response of body acceleration has the same frequency component as the interference torque of the excitation sources, the body vibration caused by torque ripple become obvious during the starter drive the engine and regenerative braking mode at low engine speed. The angular acceleration of the planetary gear system significantly increase due to the torque fluctuations caused by the working mode switches. This research can be used to support the design and improvement of noise and vibration behavior of Series-parallel hybrid powertrain system.