Modeling And Controller Design Of High Pressure Common Rail Sysytem For Marien Diesel Engine

On basis of RT-flex 48T-D marine low-speed diesel engine produced by W?rtsil? Company, the thesis researches on its common-rail fuel injection system. Firstly the working principle of its whole hydraulic control system is introduced in the thesis. And a mathematical model of RT-flex48’s high pressure common-rail system is established. To satisfy the real-time request, the mathematical model is simplified and an appropriate real-time calculation method is used. The simulation program of the common-rail fuel injection system which is developed with Simulink is downloaded to the rapid prototyping device NI Company produced. By way of such method, a virtual fuel system made up of software and hardware is built.Secondly, the thesis proposes control algorithm for the high-pressure fuel system of RT-flex48T-D on the basis of deep research. And the control algorithm is rapid deployed on the rapid prototyping device composed of FPGA and MCU for purpose of controller design. The control algorithm for RT-flex 48 is significant different from traditional control algorithm for common-rail diesel. The control method of fuel injection quantity is no longer dependent on MAP graph of injection pulse width. In addition, taking the closed-loop control technique, the injection timing is modified in the process of operation. Research on the control algorithm for RT-flex 48 will be a valuable experience, which provides effective help for the research and development of the domestic large-scale low-speed diesel engine.Finally the thesis studies the dynamic characteristics of key parts in RT-flex 48 fuel system by off-line simulation, and analyses the primary influencing factor. The fuel system controller deployed in this thesis is connected to the virtual fuel system, which realizes a closed-loop real-time simulation for the control algorithm. In real-time environments, the fuel injection quantity control and rail pressure control are tested, which indicates that the control algorithm has good control effect.