Experimental Investigation of Deterministic and Random Cyclic Patterns in HCCI Engine using Symbol Sequence Approach

Homogeneous charge compression ignition (HCCI) combustion emerged as promising technology for automotive pollution reduction. One of the major challenges for commercial application of HCCI combustion engine is to control the combustion in different engine operating conditions. Characteristics of HCCI cyclic variations are required for efficient control of combustion phasing. Cyclic variability has both stochastic and deterministic components. In this study, cyclic variations of IMEP and combustion duration in a HCCI engine are analyzed using symbol sequence method. To analyze the cyclic variations, 1500 consecutive engine cycle data are logged and processed. Results reveal that there is deterministic component in cyclic variations, which could lead to effective control strategies. Results confirm that in symbol sequence method optimal combination of number of partition and sequence length is dependent on engine operating conditions and selected combustion parameters. It is also found that controller should have information about more than just immediate previous cycle for effective control of HCCI engine.