Research On Key Technologies Of Free Piston Linear Generator

Free piston engine(FPE)integrated with linear generator(LG)become free piston linear generating system(FPLGS).Free piston stirling engine(FPSE)is characterized with high heat efficiency,little emission,low noise and package sealed working medium without gas exchange,and thus is one of promising energy supply method for deep space exploration.As LG playing key role in FPSE,for purpose of improving efficiency and dynamic performance of FPLGS,the double stator transverse flux permanent magnet linear machine(DS-TFPMLM)is proposed,studied and validated by experiments.Base on theory of FPLGS,FPLG model selection is performed.Firstly,flux switching permanent magnet linear machine(FSPMLM)is analyzed and a novel machine topology is derived.The derivative machine is analyzed by cogging model.Secondly,the tubular permanent magnet linear machine(TPMLM)is studied with emphasis on how cutting deviation affecting cogging force.Finally,single-stator and double stator TFPMLM is compared.Simulation results show that,1)FSPMLM has heavy mover and larger voltage regulation,derivative FSPMLM reduce cogging force to 1.57%.2)TPMLM has heavy mover and difficult lamination would cause trouble in larger iron loss.3)DS-TFPMLM has lighter mover,better dynamic performance.As results,TFPMLM is chosen to satisfy requirements of FPLGS.Single phase DS-TFPMLM is proposed to improve efficiency and decrease power postprocessing difficulty.Field distribution,induced voltage and cogging force are researched.Machine dimensions are optimized to satisfy design conditions.Influence of motion stroke,stator length,air gap and magnet dimension are analyzed.Results show that,the cogging force of DS-TFPMLM is mainly decided by stator length and magnet length.FPLGS operates in a high temperature environment.Thermal analysis is necessary for DSTFPMLM operating safety and efficiency.Firstly,compute and analyze heat source and thermal conductivity coefficients,evaluate influence of temperature rise on electromagnetic performance.Build up DS-TFPMLM thermal field model,study influence of slot fill rate and lacquer dipping process on heat dissipation,and evaluate machine temperature rise in normal and space environment.Results show that,1)temperature rise of DS-TFPMLM decrease 14.7 ? while slot fill rate increase from 0.6 to 0.8.2)normal and space environments make little difference for DS-TFPMLM temperature rise.A DS-TFPMLM prototype and its test rig is fabricated.Test items include cogging force,no load and load behavior,temperature rise and so on.Test results show that,1)DS-TFPMLM cogging force is 8.2 N,with 0.8 N larger than simulation result when motion stroke is 20 mm.2)no load induced voltage is tested 43.1 V,with 2.9 V lower than simulation result when oscillating frequency is 19.75 Hz.The results show that the simulation results is almost the same as test results.