Under actuated air path control of Diesel engines for low emissions and high efficiency

This paper presents a new method for feedback control using the Exhaust Gas Recirculation (EGR) valve and Variable Geometry Turbine (VGT) of a diesel engine. The controller effectively counteracts disturbances in NOx and PM emissions while maintaining the fuel efficiency. It is shown that by using a new combination of outputs, the controlled system has very good robustness properties. Using a mean-value engine model, which is extended with an emission model, the performance of the controlled system is examined in a simulation study with various applied disturbances; the feedback controller is shown to reduce the variation of emissions and pumping losses by 80–90 %. Compared to open loop control, the feedback controlled system has lower overall emissions by 14 % in NOx, 19 % in PM and a simultaneous 0.7 % improvement of the brake specific fuel consumption is achieved