Research On Real-time Model Of Natural Gas Engine And Intelligent Control Strategy Of Speed

In recent years,because of the promotion of energy conservation and emission reduction and the adjustment of energy structure,the shipbuilding industry has begun to shift from the traditional diesel engine to the natural gas engine.Compared with the control of the speed of the diesel engine,the natural gas engine needs to coordinate the air intake amount and the gas injection amount at the same time,resulting in the control accuracy under steady-state conditions and the response performance under transient conditions.Therefore,the speed control of natural gas engines is one of the focuses of current research.At the same time,since the development of traditional electronic control systems requires a lot of manpower,material resources and other resources,the development of electronic control systems based on engine models has become the main means at present.Such engine models must be able to meet the real-time requirements of electronic control system development and have certain accuracy,so there is a higher requirement for the construction method of real-time models.This paper analyzes the basic theory of natural gas engine modeling.Under the premise of fully reflecting the structural characteristics of natural gas engine and meeting the functional verification requirements of the control system,the modular modeling method is adopted,and the average value is built on the Matlab/Simulink simulation software platform.The real-time simulation model of YC6 K natural gas engine was established by the combination of mode,filling and MAP method,and the simulation analysis was carried out.The results show that the single-step calculation time of the established natural gas engine model is in the range of 0.0910-0.0955 ms,which is within 50% of the system step size of 0.2ms,it can meet the real-time requirements of the development of the electronic control system.Through simulation and test results,the simulation accuracy of the natural gas engine model can reach more than 90%,and it has high simulation accuracy.Taking the throttle opening and the gas injection quantity as the key control variables,the influence of the intake air quantity and the gas injection quantity control characteristics on the speed regulation characteristics of the natural gas engine is studied.Based on the research results,a double closed loop of speed and air-fuel ratio based on fuzzy-PID with feedforward composite control strategy is developed.At the same time,the dSPACE real-time simulation platform is used to verify the speed control strategy offline and online.The results show that compared with the traditional PID control strategy,the natural gas engine speed control strategy developed in this study can not only improve the control accuracy under the steady state,but also improve the response speed under Transient.It has a better adaptive ability.