Research On Dielectric Characteristics And Influencing Factors Of PEEK Materials

High-voltage and high-power press-pack IGBT(Insulated Gate Bipolar Transisitor)device is a full controlled power semiconductor device with high power density,high reliability and easy to be in series,which is the core device for manufacturing various kinds of flexible HVDC transmission equipment.In the process of independent research and development of press-pack IGBT devices,its electrical insulation performance will be one of the most critical challenges.At present,a kind of press-pack IGBT inner submodule under development uses polyether ether ketone(PEEK)as the material of the outer insulation framework.Under this complex condition,dielectric properties of PEEK material will directly affect the electric field distribution of the whole submodules,thus affect the insulation and reliability of the press pack IGBT submodules.First,the effects of frequency on the dielectric properties of PEEK material are studied.The PEEK dielectric properties test platform in frequency domain is designed and constructed to meet the application conditions of the insulation framework of the press-pack IGBT device,and it can test the dielectric properties of PEEK material in the frequency range of 10-2hz?106Hz.The wideband dielectric spectrum of PEEK material is obtained,and on the basis of measurement results of wideband dielectric spectrum the mechanism analysis of the wideband dielectric response of PEEK material is carried out,and a dielectric relaxation model that can accurately describe the wideband dielectric responses of PEEK material is obtained.Secondly,the effects of electric field intensity on the dielectric properties of PEEK material are studied.The PEEK dielectric properties test platform in time domain is designed and constructed to meet the application conditions of the insulation framework of the press-pack IGBT device,and it can test the dielectric properties of PEEK material in the electric field intensity range of 10MV/m?70MV/m.The time-domain dielectric properties of PEEK materials under different electric field intensities are obtained,the dielectric properties of PEEK material and the relationship between the dc conductivity and the electric field intensity are obtained,and the empirical model between the dc conductivity and the electric field intensity of PEEK material is given.Finally,the effects of temperature on the dielectric properties of PEEK material are studied.The dielectric properties of PEEK material under electrothermal composite stress are tested by introducing a temperature module into the platform of frequency domain dielectric properties and time domain dielectric properties.At the same time,the PEEK material is subjected to DSC thermal analysis to obtain the glass transition temperature of the PEEK material,and the influence of temperature on the wideband dielectric properties of the PEEK material is analyzed,as well as the influence of temperature at high field intensity on the low-frequency dielectric properties and dc conductivity of the PEEK material.