Electronic throttle and wastegate control for turbocharged gasoline engines

Turbocharging of gasoline engines has gained renewed popularity as a means to improve fuel economy and CO2 emissions. Modern engines have advanced technology actuators such as electronic throttle and variable valve timing, in addition to wastegate. Proper control of system actuators is critical to achieving the full benefit of this technology. This paper presents system analysis and control development for a turbocharged gasoline engine equipped with wastegate and electronic throttle. A nonlinear mean value model for the system is presented. The nonlinear model is linearized at multiple operating points and its behavior analyzed using the systems approach. A gain scheduled, decentralized controller is designed to track the intake manifold and boost pressures to meet transient, as well as steady state requirements. A multi-variable control approach is also considered to alleviate tradeoffs inherent in decentralized design.