Study On The Key Technology Of Pulsed Power With Propylene Carbonate

Liquid dielectric has been widely used as the energy storage medium in pulse forming line(PFL)due to its high density,good self-healing and easy-shaping.The ideal storage liquid dielectric should meet the requirements of high permittivity,high breakdown strength and high resistivity,whereas presently liquids used as the energy storage medium in engineering applications can not completely satisfy.In this case,as a new high-energy-storage-density liquid dielectric,the propylene carbonate(PC)is selected to developing researches on the key technology of pulsed power by comparing with other liquids.The researches set a guidance significance for improving energy storage properties of liquid dielectrics and developing of compact pulsed power facilities.Contents are shown as follows.First of all,in the case of the low resistivity of commercial PC,the PC purification system is designed.After deionizing and degassing by this system,the resistivity of PC will increase from 4 M?·cm to 263 M?·cm.Then the experiments of resistivity maintaining of purified PC and 25% ethylene glycol/deionized water mixture are carried out.The results show that the resistivity of purified PC decreases from 263 M?·cm to 31 M?·cm after sealed storage for 26 days,while the resistivity of 25% ethylene glycol/deionized water mixture drops from 20 M?·cm to 7 M?·cm after sealed storage for 10 days.Through analyzing the law and reasons of resistivity maintaining,the conclusion can be drawn that PC has the superiority against water in the respect of resistivity maintaining.In that case,taking PC as the energy storage medium in PFL is beneficial to maintenance-free of pulsed power system.Secondly,the experiments of researches on the pulse insulating properties of PC/ mxylene(MX)are carried out based on the liquid pulse breakdown platform.The results indicate that the breakdown strength of 12.5%MX/PC is 25.1% higher than that of pure PC,while the breakdown strength of 20%MX/PC is 5.8% lower than that of pure PC.Therefore,the volume fraction of MX should restricted to a limited range in order to improve the breakdown strength of PC.Meanwhile,the research on the polarity effects of PC is developed in this platform.The data demonstrated that the positive breakdown voltages are respectively 37.5%,40.4% and 14.0% higher than the negative ones for the gaps of 0.5 mm,1.0 mm and 2.0 mm.In addition,another conclusion shows that when the electrode gap increases,the positive polarity of PC is weakened.Finally,based on the high/low temperature test chamber and liquid pulse breakdown platform,the liquid temperature adaptability system is designed to carry out the research of PC temperature adaptability.The research mainly demonstrates the temperature effects on the breakdown strength of PC.The results show that the breakdown strength of both flowing PC and standing PC increase with the rising temperature.Moreover,another research is developed to study the temperature effects on the intrinsic time constant of PC.The conclusion of the temperature effects on the pulse insulating properties such as intrinsic time constant,capacitance,inductance,impedance,pulse width,energy density is drawn by using the data of the experiments.It has a guidance significance for PC applying in pulsed power system by mastering the variation trend of these pulse insulating properties.