Pressure states observer for high pressure common rail fuel system based on flow model

The measured rail pressure signal is the basis of the pressure control of the high pressure common rail fuel system. However, the complexity of the rail pressure signal has a great influence on the performance of the intelligence control method when applied to the pressure control. In order to obtain the pressure states caused by the unbalanced flow in the rail pipe, a pressure states observer and a Kalman filter for the common rail fuel system has been established. For the designing of the pressure states observer, the mathematical model of the flow of common rail fuel system has also been established. Finally, simulations in the MATLAB/Simulink were carried out, and the results show that the pressure states observer decreases the maximum pressure deviation of the signals for 69.6%, the Kalman filter decreases for 54.3%. Moreover, the pressure states observer can effectively pick out the pressure changes caused by the unbalanced fuel flow from the pressure signals.