Control of dual loop EGR air-path systems for advanced combustion diesel engines by a singular perturbation methodology

This paper presents a method to control dual loop EGR air-path systems for Diesel engines running advanced combustion modes. Considering the different time scales (fast and slow) dynamics of high pressure loop EGR (HPL-EGR) and low pressure loop EGR (LPL-EGR), a decomposition control method for a singularly perturbed system was utilized to achieve systematic air-path control, including the control of temperature, pressure, and oxygen fraction in intake manifold. Variable geometry turbocharger (VGT) was used to control the pressure before a high-pressure throttle (HP-Throttle) valve to accommodate the constraints of other actuators, such as dual-loop EGR and HP-Throttle. Effectiveness of such a control methodology was shown by simulation results based on a high-fidelity GT-Power Diesel engine model.