Simulation And Structure Design Of Free Piston Linear Generator

Free piston linear generator(hereinafter referred to as FPLG)is a new power unit,coupled directly by free piston engine and linear motor.FPLG has the advantages of simple structure,high efficiency and adaptability to fuel.Due to the abolition of the crankshaft mechanism,the piston movement is too “free”,resulting in several stability problems.Therefore,the position control of piston is the key to realize the stable operation of FPLG.In this paper,two stroke double piston & cylinder direct injection FPLG is researched,and a model coupled by mechanical,fluid and electric control is built based on Simulink,whose fluid partial model is validated dependent on GT-Power.Gas transfer model and thermodynamic model of mixture in cylinder are updated for the simulation of unstable state of FPLG.With the Simulink model,FPLG operation rules and parameters influence on the operation state are analyzed.The process of gas transfer and unstable combustion and those influences on the stability of FPLG are studied deeply.Based on the study of factors that influence the stability of FPLG,an active load control strategy is designed,and tested by combining the FPLG model,significant result achieved.On the basis of simulation result of Simulink model,the prototype of the FPLG is designed and produced.Linear motor,cylinder and piston,injector,sparker,etc.are selected and purchased,Cylinder head,connecting rod,cylinder base,etc.are designed and produced.The whole model is updated according to the compression ratio,the matching between parts,air tightness and piston position limiting.Prepare for the following experiments.