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Most automobile manufacturers have developed hybrid vehicles that combine an internal combustion engine and an electric motor, fusing the advantages of these two power sources. For example, Toyota, in its Prius II, uses a highly efficient gasoline engine based on a modified Atkinson cycle featuring a variable valve timing management. This implementation of the Atkinson cycle is not the optimal solution because some of the air is first sucked from the intake manifold into the cylinder and subsequently returned. This oscillating air stream considerably reduces the thermal conversion efficiency of this cycle. This paper analyzes in detail the loss of thermal conversion efficiency of an internal combustion engine -especially for modified Seiliger and Atkinson cycles - and a proposal is made for the improvement of aspirated and supercharged engines.

The paper focuses on a system and an appropriate controller concept for advanced air management of a turbo-charged passenger car diesel engine. The proposed air management system consists of a VTG turbocharger and two separate Exhaust Gas Recirculation (EGR) loops, a cooled or non-cooled high-pressure EGR (HP EGR) and a cooled low-pressure EGR (LP EGR) loop. In the LP EGR loop, the exhaust gas leaving the particulate filter is mixed with fresh air just in front of the compressor inlet. A main model (MM) was created in Simulink to design a Nonlinear Model-based Predictive Controller (NMPC). This model is mainly founded on physical equations, allowing easy adaptation to various systems. MM is a detailed model which was developed first and which is also used for software-in-the-loop (SIL) tests of the controller with the simulated engine.