Optimal design of power-split transmissions for hydraulic hybrid passenger vehicles

Kai Loon Cheong, Perry Y. Li, Thomas R. Chase

Research output: Chapter in Book/Report/Conference proceedingConference contribution

39 Scopus citations


Hydraulic hybrid vehicles are inherently power dense. Power-split or hydro-mechanical transmissions (HMT) have advantages over series and parallel architectures. In this paper, an approach for optimizing the configuration and sizing of a hydraulic hybrid power-split transmission is proposed. Instead of considering each mechanical configuration consisting of combinations of gear ratios, a generalized kinematic relation is used to avoid redundant computation. This captures different architectures such as input coupled, output coupled and compound configurations. Generic kinematic relations are shown to be mechanically realizable. Modal operation of the transmission is introduced to reduce energy loss. The Lagrange multiplier method for computing the optimal energy management control is shown to be computationally efficient for use in transmission design iterations. An optimal design case study indicates improvement in fuel economy and smaller component sizes for the compound and input coupled power-split configurations.

Original languageEnglish (US)
Title of host publicationProceedings of the 2011 American Control Conference, ACC 2011
Number of pages6
StatePublished - Sep 29 2011
Event2011 American Control Conference, ACC 2011 - San Francisco, CA, United States
Duration: Jun 29 2011Jul 1 2011

Publication series

NameProceedings of the American Control Conference
ISSN (Print)0743-1619


Other2011 American Control Conference, ACC 2011
CountryUnited States
CitySan Francisco, CA


  • Hybrid vehicles
  • Lagrange multiplier
  • engine management
  • hydraulics
  • optimal control
  • power-split

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