Transmission Ratio Design for Electric Vehicles via Analytical Modeling and Optimization

Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademicpeer-review

12 Citations (Scopus)
182 Downloads (Pure)


In this paper we present an effective analytical modeling approach for the design of the transmission of electric vehicles. Specifically, we first devise an analytical loss model for an electric machine and show that it can be accurately fitted by only sampling three points from the original motor map. Second, we leverage this model to derive the optimal transmission ratio as a function of the wheels' speed and torque, and use it to optimize the transmission ratio. Finally, we showcase our analytical approach with a real-world case-study comparing two different transmission technologies on a BMW i3: a fixed-gear transmission (FGT) and a continuously variable transmission (CVT). Our results show that even for e-machines intentionally designed for FGT, the implementation of a CVT can significantly improve their operational efficiency by more than 3%. The provided model will ultimately bridge the gap in understanding how to efficiently specify the e-machine and the transmission technology in an integrated fashion, and enable to effectively compare single- and multi-speed-based electric powertrains.

Original languageEnglish
Title of host publication2020 IEEE Vehicle Power and Propulsion Conference, VPPC 2020 - Proceedings
PublisherInstitute of Electrical and Electronics Engineers
Number of pages6
ISBN (Electronic)9781728189598
Publication statusPublished - 18 Feb 2021
Event17th IEEE Vehicle Power and Propulsion Conference (VPPC 2020) - Virtual, Gijon, Spain
Duration: 18 Nov 202016 Dec 2020
Conference number: 17


Conference17th IEEE Vehicle Power and Propulsion Conference (VPPC 2020)
Abbreviated titleVPPC 2020
CityVirtual, Gijon

Bibliographical note

Publisher Copyright:
© 2020 IEEE.

Copyright 2021 Elsevier B.V., All rights reserved.


  • Automated transmissions
  • Continuously variable transmission
  • Electric machines
  • Electric vehicles
  • Optimization
  • Powertrains
  • Transmissions


Dive into the research topics of 'Transmission Ratio Design for Electric Vehicles via Analytical Modeling and Optimization'. Together they form a unique fingerprint.

Cite this