2020/06/08 by Théo Hofman, Hofman, Theo, Mauro Salazar +1
Engineering · #Electric and Hybrid Vehicle Technologies #FOS: Electrical engineering #Real-time simulation and control systems #Systems and Control (eess.SY) #Vehicle emissions and performance #electronic engineering #information engineering
paper · pdf · doi:10.48550/arxiv.2006.04705
openalex publication_date 2020/06/08 · openalex created_date 2022/07/26 · openalex updated_date 2026/07/28
In this paper we present an effective analytical modeling approach for the\ndesign of the transmission of electric vehicles. Specifically, we first devise\nan analytical loss model for an electric machine and show that it can be\naccurately fitted by only sampling three points from the original motor map.\nSecond, we leverage this model to derive the optimal transmission ratio as a\nfunction of the wheels' speed and torque, and use it to optimize the\ntransmission ratio. Finally, we showcase our analytical approach with a\nreal-world case-study comparing two different transmission technologies on a\nBMW i3: a fixed-gear transmission (FGT) and a continuously variable\ntransmission (CVT). Our results show that even for e-machines intentionally\ndesigned for a FGT, the implementation of a CVT can significantly improve their\noperational efficiency by more than 3%. The provided model will ultimately\nbridge the gap in understanding how to efficiently specify the e-machine and\nthe transmission technology in an integrated fashion, and enable to effectively\ncompare single- and multi-speed-based electric powertrains.\n