Research On The Magnetic Circuit Structure Design Of Cylindrical Linear Generator

Linear Stirling generator is a new type of thermoelectric converter.It is already used in space exploration,military portable power supply and micro conbined heat and power.This technology is being studied and developed.Stirling linear generator consists of linear Stirling engine(free piston Stirling engine or thermoacoustic engine)and linear generator.The piston in linear motion is connected with the mover of linear generator,forms a direct-drive power system.Without extra transmission,linear Stirling generator has less friction loss,smaller size and higher efficiency.However,in actual development,Stirling engine has great difficulties in high temperature resistant materials and dynamic seals,linear generator needs to be improved in structure design,power generation and mechanical properties because of its special structure and kinetic characteristic.In this paper,aiming at the space-oriented Stirling power system,the power generation characteristics and mechanical properties of the cylindrical linear generator are studied,and a low-power prototype with simpler structure,smaller detent force and easy to start-up is designed and assembled.Through experiments,the output characteristics and performance of linear generator are understood,which provides a reference for the development of linear Stirling generator.According to the research,there are several main problems and difficulties in linear generator:special structure makes it difficult to manufacture,detent force makes the operation unstable,and the output waveform under vibration is irregular.Firstly,the overall configuration of linear generators is determined primarily by comparing different types of linear generators.Referring to the performance parameters of existing equipment at home and abroad,the parameters of linear generator are set.Secondly,the electromagnetic model of linear generator is established by infinite element software ANSYS Maxwell.The EMF and power of linear generator under simple harmonic oscillation are studied.Results show that the single-phase winding linear generator has better ouput at the condition of simple harmonic vibration with small amplitude,which fits the linear Stirling power system.Detent force and power are related to structure.The fractional slot structure has small detent force but the power is low,the full-pitch structure has large detent force but the power is high.The stability of the vibration center is related to the force acting on the motor near the vibration center.Spring plays an important role in the whole power system.Then,the structure of stator and mover of linear generator is designed in detail by using mechanical modeling software UG.The power source and motion transfer mechanism for prototype test are selected,and the experimental system of linear generator is built.The problems found in debugging are analyzed and the experimental device is improved.Finally,experimental tests are carried out to measure and analyze the positioning force.no-load EMF waveform and output power of the linear generator.The overall performance of the prototype is evaluated and summarized,and the direction of further research and improvement is pointed out.