Second-order sliding mode strategy for air-fuel ratio control of lean-burn SI engines

Behrouz Ebrahimi, Reza Tafreshi, Javad Mohammadpour, Matthew Franchek, Karolos Grigoriadis, Houshang Masudi

Research output: Contribution to journalArticlepeer-review

45 Scopus citations


Higher fuel economy and lower exhaust emissions for spark-ignition engines depend significantly on precise air-fuel ratio (AFR) control. However, the presence of large time-varying delay due to the additional modules integrated with the catalyst in the lean-burn engines is the primary limiting factor in the control of AFR. In this paper, the engine dynamics are rendered into a nonminimum phase system using Padé approximation. A novel systematic approach is presented to design a parameter-varying dynamic sliding manifold to compensate for the instability of the internal dynamics while achieving desired output tracking performance. A second-order sliding mode strategy is developed to control the AFR to remove the effects of time-varying delay, canister purge disturbance, and measurement noise. The chattering-free response of the proposed controller is compared with conventional dynamic sliding mode control. The results of applying the proposed method to the experimental data demonstrate improved closed-loop system responses for various operating conditions.

Original languageEnglish (US)
Article number6612669
Pages (from-to)1374-1384
Number of pages11
JournalIEEE Transactions on Control Systems Technology
Issue number4
StatePublished - Jul 2014


  • Air-fuel ratio (AFR) control
  • dynamic sliding manifold
  • lean-burn engine
  • nonminimum phase system
  • second-order sliding mode
  • time-varying delay

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Electrical and Electronic Engineering


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