Control of dual-loop EGR engine air-path systems with adjustable intake manifold condition priorities

Dual-loop EGR (exhaust gas recirculation) systems can provide the authorities of controlling the engine intake manifold gas conditions for steady-state and transient operations of advanced combustion modes. Due to the inherent transport delay of an air-path system, the response of the intake manifold oxygen concentration is usually slower than those of the pressure and temperature under conventional control methods. This paper presents a control methodology for dual-loop EGR engine air-path with adjustable intake manifold gas condition priorities, which means that any of the three intake manifold indices can be set with the highest control priority to obtain fast response during transient operations. The reference governor technique and a feedforward control are combined to achieve such a control objective. An acceptable control input set is obtained and the optimal input is chosen from this set according to the priority order. Simulations are conducted on a GT-Power engine model and the results show that the proposed control methodology is valid.