Nonlinear model predictive control of a dual-independent variable valve timing engine with electronic throttle control

Significant excursions of engine variables occur during fast transients because of slow actuator responses and system dynamics. This creates adverse effects on dynamic performance and often causes emissions penalties. The challenge is particularly pronounced in engines with an increased number of actuators. In this paper, non-linear model predictive control (NMPC) is introduced to improve the dynamic response of a flexible engine system. NMPC combines advantages of both feed forward and feedback control while considering their constraints. The length of control horizon and prediction horizon are determined to achieve the dead-beat-like optimal control during transients and ensure smooth responses. The NMPC significantly improves the engine torque response and minimizes the excursions of in-cylinder variables under highly transient operation by adjusting each actuator control input simultaneously to achieve the control objectives.