Model Based Control of Exhaust Recompression Hcci

This paper presents an approach to model-based controller development for Homogeneous Charge Compression Ignition (HCCI). The control strategy for HCCI is based on a physical two state discrete time model of the process. As the trapped exhaust is pivotal in setting up the cyclic coupling, its temperature and the amount of oxygen present in it are selected as the states of the system. The model is linearized about an operating point in order to generate simple linear controllers. The states of the model, however, are not directly measurable. Hence an observer is used to generate estimates of the states, which are then used by a controller to track a desired system trajectory. Results from simulation show that the system can be controlled with some error about an operating point. Experimental results demonstrate comparable tracking, along with a reduction in the cycle-to-cycle variability of HCCI.