Research And Development Of The Electric Control System On Internal Mixing Type Multi-Point Injection Industrial Gas Engines

With the fast development and prosperity of the economy of China, requirement of energy sources increasing rapidly. As petroleum is a non-renewable energy resource, the research of alternative fuel sources become more and more important, especially on natural gas, bio-gas and coal gas. And the gaseous energy source could be the most effective alternative fuel sources in short period of time. In this paper, a set of electronic control unit (ECU) applying for multi-point injection gas engine was developed, according to the characteristics of gas engine and the operation conditions.First of all, the fundamental framework of the ECU control system has been constructed after analysis on the characteristics of that. And by using the model-based method during the development process on the ECU control system, the designers could make engagement in the establishment and calibration of mathematics model without concern about the variation of hardware or compiling the basic code, which make the development process efficiently.There are four core models in the ECU control system which are excess air ratio model, constant speed control model, gas injection valve drive model and basic engine protection model separately. The prediction of air and fuel gas flow rate has been made in the excess air ratio model by means of speed-density method that is improved and regulated with the closed-loop correction on the excess air ratio. A better stability and response can be obtained in the constant speed control model using a new PID control method. And by applying the current self-adapting algorithm, the drive current can be reduced decline as low as possible in the gas fuel injection valve drive model and therefore the life span of inject-valve can be prolonged.After finished the ECU control models, a simple engine mean value model was build using Simulink which used to test the reliability of the software control models and the response of hardware equipments. The results show that stable output of the control model can be obtained even with a sustained interference signal, which means the control model and arithmetic are reliable.Experiments have been carried out in a 12V190 industrial gas engine to calibrate the ECU control system, and the stable and the transient experimental results show that control precision and response rate of the excess air ratio and speed can satisfied with the industrial gas engine control demand. Therefore the developed ECU control system is suitable for industrial gas engine.