Design and Optimization of a Novel Dual-Motor Coupling Propulsion System with Composite Transmission

With the development of technology in the past decade, China has gradually occupied an absolute leading position in the field of electric commercial vehicles, and has achieved great success in electrified buses. However, the mature powertrain of electric buses, including the single motor direct drive and single motor equipped with reduction gear, cannot meet the needs of electric duty trucks. Though automated mechanical transmission (AMT) is a feasible solution, the power interruption and shift shock hinder its further application. Also, using dual-motor is a promising way to reduce the motor size of duty trucks. It is challenging to find an applicable and optimal architecture for duty trucks due to the diverse potential topology. In this paper, a novel dual-motor coupling propulsion system is proposed, to take advantage of lower mechanical gear pairs reaching more significant driving modes, a special composite transmission is developed. The basic configuration and operating principle are illustrated. As for the particular transmission, a dedicated gear ratio design and optimization process is put forward. Compared with traditional powertrain configuration, the proposed propulsion system can are quite compact, but can realize satisfied dynamic performance and better energy-saving potential.