Improving Transient Diesel Performance with E-Supercharging and Multiple-Input Multiple-Output Controls

Engine torque response for turbocharged diesel engines is limited by lag in air supply to the engine restricting the rate at which fuel can be delivered. This delay can lead to rich air-fuel mixtures and elevated soot emissions during transient events. Electric forced induction systems (EFIS) offer a potential solution to address both of these challenges. For this study, an electric supercharger (E-Booster) is integrated with the original forced induction system of a 4.5-L 4-cylinder turbocharged diesel engine to create a two-stage boosting system that assists induction during transients. Electric supercharger operation is managed by two control schemes, a model-based single-input single-output (SISO) and a model-based robust multiple-input multiple-output (MIMO) controller. Constant speed load acceptance (CSLA) experiments and emulated drive-cycles were performed in a dyno cell evaluating both control methods. The E-supercharged two-stage boosted engine has demonstrated significant improvements over the baseline system, showing improved engine torque-handling capabilities with reduced engine speed droop and engine speed recovery time during heavy transients. In-cylinder heat release is analyzed and its relationship to the performance changes are addressed. Additionally, transient engine soot emissions are reduced. Results are consistent using both the SISO and MIMO controllers, but improvements are further augmented with the MIMO controller showing the potential of MIMO control. Furthermore, Thus, EFIS technology when paired with MIMO control proves to be highly beneficial during transient engine operation.