Air charge control for turbocharged spark ignition engines with internal exhaust gas recirculation

This paper presents the design of transient cylinder charge control, based on a cycle-averaged mean-value model for a turbocharged spark ignition direct injection engine equipped with dual-independent intake and exhaust variable camshafts which in this paper has been constrained to variable valve overlap with symmetric cam motions. The control-oriented model, parameterized using dynamometer measurements, is shown to capture engine static and dynamic behavior of throttled conditions. The transient effects of throttling and variable valve timing on the cylinder charge over part-load and lightly boosted conditions are first analyzed to investigate the dynamic interactions between the electronic throttle and the valve overlap through variable camshafts. Given the fast dynamics of the electronic throttle actuator, a nonlinear feedforward and feedback throttle compensator, in reference to its static set-points, is employed here to improve the transient response of cylinder charge. It has been shown in simulation results that the combined use of both compensators can considerably improve transient engine performance.