Design and performance simulation of an electrically driven transmission based on hydro-mechanical torque converter

To mitigate stall conditions in electric drive motors and improve low-speed dynamic performance of electric vehicles, a design of electric drive transmission by employing the adaptation of a converging-differential hydro-mechanical torque converter configuration is innovatively proposed. The transmission is simple in structure, and has two operating modes of fixed ratio transmission mode and converging-differential hydro-mechanical torque transmission mode. This study conducts a focused analysis of the speed-torque conversion mechanism in the converging-differential hydro-mechanical torque transmission mode, complemented by comprehensive modeling and simulation to evaluate its implementation efficacy in electric vehicle transmission systems. Simulation results demonstrate that equipping this transmission enables significant downsizing of the drive motor power, reducing it from 120 kW (benchmark vehicle specification) to 60 kW while maintaining comparable climbing and acceleration performance. Compared to a vehicle equipped 60 kW motor without this transmission: acceleration performance shows a 17.97% improvement; gradeability has been significantly increased by double; motor efficiency exhibits a 4.91% relative enhancement.