Real-Time Performance and Driveability Analysis of a Clutchless Multi-Speed Gearbox for Battery Electric Vehicle Applications

Abstract

Due to the electric machine torque bandwidth characteristic and good efficiency throughout its operational points, battery electric vehicles (BEVs) are typically equipped with a single-speed gearbox (SSG). Nevertheless, multi-speed gearboxes have been investigated for BEVs’ powertrain application as multiple gear ratios add the possibility of keeping the EM operating in a better efficiency region, thus reducing vehicle energy consumption and increasing dynamic performance. At the same time, driving simulators have gained momentum in industry and academia. Simulators render a faster, cheaper, and safer research and development process since it is possible to analyze the project at a system level before building prototypes. In addition, driving simulators allow the driver’s perception of gear shifting times, shift hunting, and vehicle jerk to be considered during the development phase. Combining the trends mentioned above in the automotive segment, we modeled single-and two-speed BEV models in MATLAB/Simulink. We performed a performance and driveability analysis in a static driving simulator. The preliminary results of adopting an efficiency-based shifting schedule and testing different gear shifting duration times indicate the importance of considering the vehicle’s dynamic behavior when employing multi-speed gearbox in BEVs.