Effect Of Nanoparticles Plasma Treatment On Corona Resistance Of PI Composite Films

The inverter-fed traction motor is one of the core equipment of the high speed train,and its insulation state affects the safe operation of the train.PI is widely used in the interturn insulation of the inverter-fed traction motor because of its excellent properties.Due to the effect of high frequency pulse,the inverter-fed traction motor still appears premature failure.Though adding nanoparticles in the PI can improve the insulation properties of the materials.However,the agglomeration of nanoparticles restricts the further improvement of the performance of nanocomposite,and the surface modification can improve this.In recent years,plasma has been applied to surface modification of polymer because and it is expected to be used for the surface modification of nanoparticles.Therefore,it is of great significance for improving the insulation life of the inverter-fed traction motor to study the effect of nanoparticles plasma trentment on the corona resistance of PI nanocomposite films.Nanoparticles plasma modification platform was built in this thesis and nano alumina was modified by plasma and KH550.Then PI/Al₂O₃ films were prepared by in-situ polymerization,and the dispersion of nanoparticles in films were observed by SEM,besides the chemical structure of the films were analyzed by FTIR,and the dielectric properties of films were studied based on the dielectric spectrum.The TSC carves were obtained and the trap energy density distribution were calculated.The space charge distribution of films was measured by PEA method.The influence of hetero polar space charges on the electric field was explored.The change of chemical bonds on the surface of the nanoparticles before and after the plasma modification was studied.And the interfacial properties were analyzed based on interface theory.The mechanism of nanoparticles plasma modification was also analyzed,and the effect of the plasma modification of nanoparticles on trap characteristics of film was proved.The insulation life of films was measured,and the insulation life characteristics based on Weibull distribution were analyzed.The aging of PI/Al₂O₃ films was also carried out.The effect of plasma modified nanoparticles on the microcosmic process of corona aging was investigated from dielectric properties,trap characteristics and chemical bond fracture.Finally,the mechanism of enhancing the corona resistance of PI/Al₂O₃ films was elucidated from the bombardment effect of charges on PI chains.