Physics-based closed-loop control of phasing, peak pressure and work output in HCCI engines utilizing variable valve actuation

Homogeneous charge compression ignition (HCCI) represents a promising combustion strategy for future engines. However, HCCI lacks an easily identified combustion trigger and, when achieved via variable valve actuation (VVA), includes cycle-to-cycle coupling through the exhaust gas. This makes controlling the process decidedly non-trivial. To address these issues, the development of a closed-loop controller for HCCI combustion phasing and peak pressure is outlined. Through a series of simplifications, the essential physics behind the combustion process is captured in a low-order dynamic model. This model proves amenable to a simple control structure based on dynamic feedback linearization. Results from both simulation and experiment show that cycle-to-cycle control of VVA-induced HCCI can be achieved using this physics-based approach.