Dynamic control of a SI engine with variable intake valve timing

Abstract

SUMMARYEngines 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.

Model reduction of automotive engines using perturbation theory

“…with Lipschitz constant L. Let T (t) andT (t) be the solutions of (7) and (8), respectively, such that…”

“…The time continuity of the control inputs can be assumed because inputs to the engine (like throttle and waste-gate) vary smoothly with time. Thus (7), which governs dynamics of the temperatures, can be approximated by equations (8). Accordingly, the original system Σ can be approximated by the following system…”

Inherent limitations and control design for camless engine idle speed dynamics

“…The simple mathematical representation developed in the previous sections allows us here to demonstrate that the camless idle speed system is an unstable nonlinear system with considerable delays associated with the sensing/actuating interface and the discrete nature of the torque generation. Without downplaying the issues associated with the complex nonlinearities of the system [13], we are focusing on small-signal analysis and employ techniques pertinent to linear time invariant (LTI) systems. Linearization at a nominal point that corresponds to idle operation shows that the open-loop dynamics of the unthrottled camless engine have a right-half plane (RHP) pole and a signi"cant time delay.…”

AFR control for motorcycle engine using smith predictor and h<inf>&#x221E;</inf> control

“…Other works propose to control the air flow using addtional actuators as secondary throttles and intake valves [6]- [8].…”