Dynamic control of a SI engine with variable intake valve timing

Engines equipped with a means to actuate air flow at the intake valve can achieve superior fuel economy performance in steady state. This paper shows how modern nonlinear design techniques can be used to control such an engine over a wide range of dynamic conditions. The problem is challenging due to the nonlinearities and delays inherent in the engine model, and the constraint on the air flow actuator. The controller is designed on the basis of a mean-value model, which is derived from a detailed intake stroke model. The control solution has two novel features. Firstly, a recovery scheme for integrator wind-up due to input constraints is directly integrated into the nonlinear control design. The second novel feature is that the control Lyapunov function methodology is applied to a discrete-time model. The performance of the controller is evaluated and compared with a conventionally controlled engine through simulation on the detailed engine model. Copyright # 2003 John Wiley & Sons, Ltd.