A parameter-varying filtered PID strategy for air-fuel ratio control of spark ignition engines

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• 作者：Behrouz Ebrahimi^a ; Reza Tafreshi^a ; ^{reza.tafreshi@qatar.tamu.edu} ; Houshang Masudi^a ; Matthew Franchek^b ; Javad Mohammadpour^b ; Karolos Grigoriadis^b
• 关键词：AFR control ; Time-varying delay ; Non-minimum phase system ; Dynamic compensator ; Spark ignition engine
• 刊名：Control Engineering Practice
• 出版年：2012
• 期刊代码：43_09670661
• 类别：et
• 出版时间：August, 2012
• 卷：20
• 期：8
• 页码：805-815
• 文件大小：1547 K

摘要

In this paper, a new synthesis method is presented to control air-fuel ratio (AFR) in spark ignition engines to maximize the fuel economy while minimizing exhaust emissions. The major challenge in the control of AFR is the time-varying delay in the control loop which restricts the application of conventional control techniques. In this paper, the time-varying delay in the system dynamics is first approximated by Pad茅 approximation to render the system dynamics into non-minimum phase characteristics with time-varying parameters. Application of parameter-varying dynamic compensators is invoked to retrieve unstable internal dynamics. The associated error dynamics is then utilized to construct a filtered PID controller combined with a parameter-varying dynamic compensator to track the desired AFR command using the feedback from the universal exhaust gas oxygen sensor. The proposed method achieves desired dynamic properties independent of the matched disturbances. It also accommodates the unmatched perturbations due to the dynamic compensator features. The results of applying the proposed method to experimental numerical data demonstrate the closed-loop system stability and performance against time-varying delay, canister purge disturbances and measurement noise for both port fuel injection engines and lean-burn engines.