승용디젤엔진 EGR 및 VGT 제어시스템의동적특성을 고려한 Decoupler 설계 연구

Abstract

This paper proposes a decoupler design method to reduce interaction between exhaust gas recirculation(EGR) and variable geometry turbocharger (VGT) systems in passenger car diesel engines. The EGR valve and VGTvane are respectively used to control air-to-fuel ratio (AFR) of exhaust gas and intake pressure. A plant model for EGRand VGT systems is defined by a first order transfer function plus time-delay model, and the loop interaction betweenthese systems is analyzed using a relative normalized gain array (RNGA) method. In order to deal with the loopinteraction, a design method for simplified decoupler is applied to this study. Feedback control algorithms for AFR andintake pressure are composed of a compensator using PID control method and a prefilter. The proposed decoupler isevaluated through engine experiment, and the results successfully showed that the loop interaction between EGR andVGT systems can be reduced by using the proposed decoupler. Furthermore, it presents stable performance even offfrom the designed operating point