Development of a Control-Oriented Cylinder Air-Charge Model for Gasoline Engines with Dual Independent Cam Phasing
2022-01-0484
03/29/2022
- Event
- Content
- Cylinder air-charge is one of the most important parts of the torque control in a gasoline engine, due to the necessity to keep a stoichiometric air-fuel ratio for the three-way catalyst to work efficiently. Throttle and phasing of the camshafts are actuators that have a big effect on the cylinder air-charge, this results in a cross-coupling between the actuators. One approach to handle the cross-coupling that occurs with multiple actuators is to use model predictive control (MPC), that handles the cross-coupling through the use of models and optimization. Models that support computation of gradients and hessians are desirable for use in MPC, which is not supported by a look-up table approach. Through the use of cylinder pressure measurements, from a 4 cylinder engine with dual independent cam phasing, and simulation, the effects from variable valve timing on the cylinder air-charge are investigated during the valve overlap period. A phase described using the path of least resistance is found to have an inhibiting effect on the backflow of residual gases during the overlap period. From the analysis of the effects on air-charge, a model is proposed for the volumetric efficiency. As the model proposed fits into the Mean Value Engine Model (MVEM) framework it is especially useful for control design. The model is validated against stationary measurements and the results show that the proposed model capture the important behaviors and changes in the air-charge related to the variable valve timing. Making it suitable for usage in a MPC framework.
- Citation
- Holmbom, R., and Eriksson, L., "Development of a Control-Oriented Cylinder Air-Charge Model for Gasoline Engines with Dual Independent Cam Phasing," SAE Technical Paper 2022-01-0484, 2022, .