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

Free piston engine generators are under investigation by a number of research groups in recent years for their characteristics of high energy conversion efficiency and good fuel adaptability.Linear generator is a device used to accomplish electromechanical energy conversion and control the motion free piston.So its performance has great influence on the performance of free piston engine.For the application of single-cylinder four-stroke free piston engine,a type of cylindrical type of moving coil linear generator and its four quadrant reversible controller are designed.Then the simulation analysis and prototype test are carried out.The structure of device is described and the four-stroke work cycle of the device is presented.The dynamic simulation model is established based on the Matlab/Simulink,and the simulation is done by the parameters of the prototype.The performance requirements of the linear motor are determined.A moving coil PM linear motor is confirmed according to the requirements.The calculation formulas for electromagnetic force constant is deduced.The finite element analysis of electromagnetic field is completed through Maxwell,and the force performance and the coil inductance are calculated.A linear motor prototype is assembled.Based on the working characteristics of the four-stroke work cycle,a linear motor controller is designed,and the control strategy is proposed.Corresponding to the control strategy,the control circuit is designed based on the H-bridge circuit.The controller simulation model is built in Simulink combined with the engine dynamic characteristic simulation model.And the simulation of the working process of the linear motor controller has been completed.The experimental prototype of the free-piston engine generator is assembled and tested.According to the simulation analysis and experiment results,the electromagnetic force constant of the linear generator is 31.1.The current response time is about 0.6ms,and the power generating efficiency is 95.2%.The linear motor system designed in this paper is able to meet the requirements of the single cylinder four-stroke free-piston engine generator.