Robust common rail pressure control algorithm for light-duty diesel engines

Abstract

This paper proposed a robust common rail pressure control algorithm for light-duty diesel engines. In this study, rail pressure and the driving current of pressure control valve are selected as a performance variable and a control input, respectively. The proposed algorithm is composed of feedforward and feedback controllers. In order to achieve fast tracking performance, the feedforward control algorithm is derived from the empirical model which represents physical relation between the driving current of the pressure control valve and the common rail pressure. The feedback algorithm is designed using integral control method to compensate the modeling error of the feedforward algorithm. According to the quantitative feedback theory, the feedback algorithm is robustly designed with consideration of the plant model uncertainty which is originated from the metering unit's operating conditions. The proposed common rail pressure control algorithm was validated through various conditions of engine experiments. From the experimental results, it is observed that the algorithm shows a good degree of tracking performance and robustness.