Research On Current Waveform Of Resonant Converter Applied To Dielectric Barrier Discharge Polymer Surface Modification

Disciplinary crossing and integration has been a significant method to solve all kinds of problems in current society with the progress of science technology.Plasma surface modification technology which is combined of three subjects(Power Electronics,Plasma Science and Materials Science)is applied to improve surface performance of various materials.Dielectric Barrier Discharge(DBD)is a common discharge pattern in plasma surface modification technology.And it’s widely used in industry because it can produce low-temperature plasma in atmospheric pressure.Voltage source resonant converter is the commonest DBD power supply in industry.Its power,frequency and treatment time are important factors which have influence on material surface modification effect,and have been studied a lot.Besides this,the relationships between current waveform and material surface treatment effect haven’t been mentioned yet.So in this dissertation,current waveform of resonant converter applied to DBD polymer surface modification was studied.In order to research the effect of current waveform in resonant converter on polymer surface modification,current waveform must be adjustable while load power and frequency must be constant.That is the power and current waveform are decoupling when frequency is fixed.So first of all,voltage source resonant converter working in continuous current mode(CCM)and discontinuous current mode(DCM)were analyzed in time domain,and two prototypes were designed according to corresponding system parameters.The adjustment method of current waveform and its coupling character with power were analyzed and verified through simulation and experiment.The results manifest that current waveform can be changed by adjusting resonant inductance.But current waveform parameters(discharge width and discharge peak current)are coupling with power in CCM and cannot be adjusted independently,while in DCM they are decoupling with power and can be adjusted freely.As a result,voltage source resonant converter working in DCM can be used to study the impact of current waveform on the effect of polymer surface modification.Then the impact of current waveform on material surface modification effect was researched under the same condition of power and frequency taking an example of biaxially-oriented polypropylene(BOPP),casting polypropylene(CPP)and polyethylene terephthalate(PET).Based on the research above,the relationships between resonant inductance and DBD load power were further studied under the same condition of frequency and surface treatment effect taking an example of BOPP.And the experimental results indicate that smaller resonant inductance in DCM contributes to shorter discharge width and higher discharge peak current,leads to smaller material contact angle and better surface modification effect compared with CCM.At the meantime,smaller resonant inductance in DCM brings about smaller DBD power and realizes energy conservation when getting to the same surface treatment effect.It is manifested that better effects of surface modification and energy conservation were obtained by changing current waveform to make its discharge width shorter and discharge peak current higher.At last,taking a comprehensive view of experimental conclusions above,the optimization idea of selecting working mode and resonant inductance in voltage source resonant converter for different applications applied to engineering practice is obtained.