Physics-Based Model Predictive Control of HCCI Combustion Phasing Using Fast Thermal Management and VVA

Homogeneous charge compression ignition (HCCI) is a promising internal combustion engine concept. It holds promise of combining low emission levels with high efficiency. However, as ignition timing in HCCI operation lacks direct actuation and is highly sensitive to operating conditions and disturbances, robust closed-loop control is necessary. To facilitate control design and allow for porting of both models and the resulting controllers between different engines, physics-based mathematical models of HCCI are of interest. This paper presents work on a physical model of HCCI including cylinder wall temperature and evaluates predictive controllers based on linearizations of the model. The model was derived using first principles and formulated on a cycle-to-cycle basis. The resulting model was of second order with two inputs and two outputs. Measurement data including cylinder wall temperature measurements was used for calibration and validation of the model. Predictive control of the combustion phasing was then evaluated experimentally using ethanol as fuel. The control signals were the intake temperature and the inlet valve closing timing. The control performance was evaluated in terms of response time and steady-state output variance. Multi-cylinder control experiments were also carried out.