The Prototype Design And Experimental Research Of A Free Piston Engine Generator

Free-piston engine generator(FPEG)has the advantages of high energy efficiency and good fuel adaptability.It is one of the research hotpots of new energy vehicles in recent years.On the basis of the original four-stroke FPEG of the research group,this paper completed the prototype design and experimental study of a two-stroke FPEG,including following aspects:(1)The overall scheme of the two-stroke FPEG was determined,and the selection and design of various subsystems such as combustion subsystem,motor subsystem and power converter were completed.The working process of the FPEG and the law of piston movement are planned,and the cyclic flow process of the system energy is analyzed.(2)The mathematical description of each subsystem was established.The simulation model of the FPEG was presented in MATLAB,and the system was simulated.The basic performance parameters and working characteristics of the FPEG are analyzed.The effect of combustion duration,combustion quality factor and piston quality on the dynamic characteristics of the FPEG are simulated.(3)The typical operating conditions in the cold start-up process and stable operation of the FPEG are analyzed.The cold start-up process control strategy based on the in-cylinder cycle indication work is proposed.The iterative learning control strategy and control strategy based on peak pressure are proposed for different strokes in the stable operation.The control strategy is simulated based on the simulation model.(4)The prototype of a two-stroke FPEG with cylinder diameter of 48 mm and a stroke of 36 mm was completed,and the experimental research on the cold start-up process and stable operation was carried out.The typical working state was used to analyzed the thermodynamic performance of the prototype,and the main reasons for the difference between the simulation data and experimental data were revealed.The simulation and tested results show that the indicated thermal efficiency of the prototype is about 38%,the indicated power is about 1500 W,the top turning points control error is less than ±0.2mm,and the bottom turning points control error is less than ±0.5mm,which can achieve efficient cold start-up and stable operation of the prototype.