Abstract
The accurate air-fuel ratio (AFR) control is crucial for the exhaust emission reduction based on the three-way catalytic converter in the spark ignition (SI) engine. The difficulties in transient cylinder air mass flow measurement, the existing fuel mass wall-wetting phenomenon, and the unfixed AFR path dynamic variations make the design of the AFR controller a challenging task. In this paper, an adaptive AFR regulation controller is designed using the feedforward and feedback control scheme based on the dynamical modelling of the AFR path. The generalized predictive control method is proposed to solve the problems of inherent nonlinearities, time delays, parameter variations, and uncertainties in the AFR closed loop. The simulation analysis is investigated for the effectiveness of noise suppression, online prediction, and self-correction on the SI engine system. Moreover, the experimental verification shows an acceptable performance of the designed controller and the potential usage of the generalized predictive control in AFR regulation application.
Highlights
The port-injected spark ignition (SI) engine is widely used in automotive production vehicles, which is equipped with a three-way catalytic converter (TWC) to reduce the exhaust emissions
An adaptive air–fuel ratio (AFR) controller design for the port-injected SI engine is presented in this work
To regulate the exhaust gas AFR at the reference value, the AFR path and SI engine dynamic modelling was implemented based on mean value engine model (MVEM)
Summary
The port-injected spark ignition (SI) engine is widely used in automotive production vehicles, which is equipped with a three-way catalytic converter (TWC) to reduce the exhaust emissions. For accurate AFR control, correct estimation of the intake air mass in the cylinder, the right amount of fuel injection, and the closed-loop AFR regulation based on the exhaust gas oxygen (EGO) sensor are three main practical aspects [1]. The look-up tables are calibrated at different engine operating conditions for open loop control, and the PID controller compensates the output error based on the EGO sensor measurement. This traditional control scheme is stable, the calibration of look-up tables and gain parameters of the PID controller are time-consuming and may not guarantee the control performance due to the engine aging and parameters varying. The AFR dynamical modelling and the specific problem of stoichiometric AFR regulation are investigated for the port-injected SI engine. Using the simulation analysis and experimental validation, we investigate the effectiveness of the proposed method
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