Model-based Decoupling Control of VGT and EGR with Active Disturbance Rejection in Diesel Engines

Exhaust gas recirculation (EGR) system and variable geometry turbocharger (VGT) system are applied in diesel engine to reduce PM and NOX. Cooperative control of EGR and VGT has tremendous impact on the emission reduction. In order to gain more fine-grained control of intake mass flow rate and intake boost pressure, a new decoupling method based on active disturbance rejection control (ADRC) beyond the traditional feedback control is proposed in this paper. When EGR valve controls the intake mass flow rate, the fluctuation of air mass caused by VGT is regarded as disturbance, estimated and cancelled by ADRC, so does the boost pressure control. Meanwhile, a model based dynamic feed-forward controller is applied to further speed the system up. Simulation results show that the response speed and tracking accuracy of both boost pressure and intake mass flow rate are dramatically enhanced simultaneously in various transient conditions. Furthermore, the proposed method also has remarkable advantages over traditional solution in terms of disturbance rejection performance.