Research on Rail Pressure Control of High-Pressure Common Rail System for Marine Diesel Engine Based on Controlled Object Model

Abstract

The common rail pressure of a marine diesel engine high-pressure common rail system is typically controlled by a PID (Proportional Integral Differential) algorithm, which has problems with both overshoot and response delay. In this paper, the control method based on controlled object model for rail pressure is studied. The control model for a high-pressure common rail system is established within the controller. Through the developed control model and the current actual rail pressure obtained by real-time acquisition, the control variables issued by the controller to the controlled object are predicted and calculated. The fuel supply required in the whole high-pressure common rail system is calculated in advance, with the fuel supply then taken as the input value for the driving model in order to calculate the PWM control signal required by the high-pressure oil pump. A PWM control signal is used to control the proportional valve opening of the high-pressure oil pump, and then control the fuel pressure in the common rail pipe. In order to verify the correctness and control effects of the rail pressure control strategy based on controlled object model, a real-time simulation of the high-pressure common rail system has been developed by combining calculation equations with a MAP data query, which ensures real-time performance. At the same time, the real-time simulation of the high-pressure common rail system shows that the error between the simulation’s calculation and the actual test data is less than 5%, and thus model accuracy is guaranteed. The control method based on controlled object model is combined with the real-time simulation model for the high-pressure common rail system to verify the control strategy function, and the control effect is then compared with that of the PID control. Comprehensive verification shows that the control strategy based on controlled object model can significantly improve the response delay and overshoot of PID control.

Keywords

• Marine diesel engines
• model-based control
• high-pressure common rail system