Hybrid Robust Control for Engines Running Low Temperature Combustion and Conventional Diesel Combustion Modes

This paper describes a hybrid robust nonlinear control approach for modern diesel engines running low temperature combustion and conventional diesel combustion modes. Using alternative combustion modes has become a promising approach to reduce engine emissions. However, due to very different in-cylinder conditions and fueling parameters for different combustion modes, control of engines operating multiple combustion modes is very challenging. It becomes difficult for conventional calibration / mapping based approaches to produce satisfactory results in terms of engine torque responses and emissions. Advanced control techniques are then demanded to accomplish the tasks. An innovative hybrid control system is designed to track different key engine operating variables at different combustion modes as well as avoid singularity which is inherent for turbocharged diesel engines running multiple combustion modes. A finite state machine based supervisory controller with a dedicated switching mechanism and two sliding mode controllers consist of the entire system. The performance of the control system is evaluated on a modern light-duty diesel engine. Compared with those of calibration-based approach, much improved performance, in terms of fast and smooth responses as well as significantly alleviated calibration efforts, were observed.