Control of a Two-Stage Turbocharged Diesel Engine Air Path System for Mode Transition via Feedback Linearization

This paper presents a nonlinear control design for a Diesel engine air path system with a two-stage turbocharger. The proposed design aims at improving the robustness and smoothness of the system response during mode transitions, namely by coordinating the available actuators to regulate the intake and exhaust manifold pressures and air mass flow rate to specified set points. A feedback linearization method is applied for the control design, based upon a simplified control-oriented air path system model. A formal stability proof of the zero dynamics is conducted to justify the selection of the appropriate system outputs and of the nonlinear control technique adopted in this study. To address model uncertainties and saturation issues for the actuators, the proposed controller is implemented using an internal model control structure. The proposed control scheme is then evaluated in simulation, using a high-fidelity engine model. Verification is conducted considering two case studies, first a simple load transient profile including a mode transition for the two-stage turbocharger, and then a portion of driving cycle.