Drive System Design for Small Autonomous Electric Vehicle: Topology Optimization and Simulation

Abstract

High driving efficiency remains challenging in autonomous electric vehicles, especially in small electric vehicle subtype. Here, we reported investigation of the structure and requirements of the drive system for those vehicles, while the motor-drive axle combined integrated driving scheme has been chosen. In the study, the power matching of drive motor as well as transmission ratio has been calculated based on the performance of the small electric vehicles, and the total gear ratio of 8.124 was determined. For better comprehensive performance and efficiency, the two-stage retarder has been designed, in which elements including high-speed shaft, low-speed shaft, gears, and differential have been examined to ensure their proof strength when the motor outputs reached the maximum torque. Notably, by utilizing topology optimization, Gear 4, the transmission unit with the heaviest weight percentage has been modified in a lightweight way, achieving a 41% reduction of the mass in emulation analysis and turned up to the target of optimization eventually.