Research On Control Strategies For Marine Medium-Speed Duel-Fuel Engine Based On Hardware-in-the-loop Platform

In order to reduce ship-source pollution,International Maritime Organization?IMO?made the emission regulations for sailing ships.It is particularly severe for NO_xemission which has stricter limits.Considering natural gas as a kind of clean fuel,dual-fuel engine achieves much lower NO_xand CO₂emissions.Therefore,the application of the dual-fuel engine technology has vast prospects for both the emission control and cost reduction.At present,China is lack of mature design methods and technical specifications as it's in a fledging study period of the marine high-power duel-fuel engine.ACD320 marine medium-speed duel-fuel engine with micro-pilot system is used as the research object in the thesis.The corresponding control strategies are studied based on ETAS FlexECU and the real time simulation model of a virtual engine.After that,the electronic software is developed combing with the experimental verification in hardware-in-loop platform.Specific tasks have been done as follows:?1?.According to the relevant rules of Classification Societies,the function modules of control system for marine dual-fuel engine are categorized in this thesis.Based on the current test conditions and the importance analysis,the main function modules,which include the mode switch of the dual fuel,the speed regulation,the closed-loop control of Lambda and LNG injection control have been studied on.?2?.The corresponding control strategies for each control function are designed.For example,the cyclic injection quantity of LNG is adjusted based on the closed-loop control of the dual-fuel engine speed.And the closed-loop control is also applied to the air-fuel ratio of a mixture in the cylinder.The excess air coefficient is considered as a feedback signal,and the control target is achieved by controlling exhaust waste gate based on the self-turning PID controller with the separation of an integral variable.?3?.Each component of the hardware-in-the-loop simulation system is proposed in this thesis.The real time simulation model is taken as a study object and the controller is FlexECU.ETAS software and hardware tool are chosen to realize the software implementation of the control strategies,due to its capacity of the connecting the controller and the actuators.Moreover,the signal transmission channels are ascertained according to their properties.?4?.The functions and variables are hooked between the application software and the low level software.The executable codes are generated after PC off-line simulating test.According to the test results,the control strategies are modified and the optimum strategies are stored in the flash memory module of FlexECU.These processes laid the foundation of hardware-in-loop simulation test.?5?.HIL calibration and measurement interface is built based on INCA software.The interface integrate the real time simulation model of the duel-fuel engine,the virtual engine carrier LABCAR,FlexECU controller and the upper-computer test software together to achieve HIL debugging test.The test results show that during mode switch process,the air-fuel ratio is controlled effectively to avoid misfiring and knocking for the virtual duel-fuel engine.What's more,the transient overshoot ratio of duel-fuel engine speed is under 2%.In the propulsion characteristic test,the fluctuations of duel-fuel engine speed in both steady and transient working cycles are less than 1%,and the excess air efficient is also close to the target value with high thermal efficiency and low NO_xemission.