Cascaded Multivariable Control of the Combustion in Diesel Engines*

Feedback control of the engine-out pollutant emissions from diesel engines is a promising approach to relax issues regarding the requirement to fulfill strict limits on the cumulative tail-pipe emissions and regarding the complexity of calibration. This contribution proposes a multivariable controller for the center of main combustion and for the indicated mean effective pressure as inner loop of a cascaded control structure for the engine-out NOx and PM emissions. The combustion controller is synthesized as a discrete H∞ controller. The controller for the emissions is based on earlier work. The real-time estimation of the combustion characteristics is provided by an embedded device with limited computational capacity. The performance of the controller is demonstrated with engine experiments.