Development Of Hardware In The AC Characteristic Testing System For Non-linear Dielectrics

Non-linear dielectrics are those materials, for which the electric conductivity or relative dielectric constant is a non-linear function of electric field. The purpose of this thesis lies in studying on AC characteristic testing system for non-linear dielectrics based on laboratory application background. The thesis focuses on researching the non-linear dielectrics characterization, the testing method and the design of testing hardware system. The suitable hardware measurement system is developed.At first, a non-linear circuit model with voltage-controlled components connected in parallel is built for non-linear dielectrics to deduce the response current function under the excitation of AC voltage. It is presented that the filed-dependent equivalent conductivity and the field-dependent relative dielectric constant are effective parameters to describe non-linear dielectrics under AC field. For J-E characteristic measurement, the extraction method of the dissipation component in response current combining hardware compensation and software signal decomposition is given. Afterwards, the AC excitation voltage source is designed by assembling the programmable signal generator made based on virtual instrument, the linear HV amplifier made base on PB50 and the experimental transformer. The main testing circuit is developed with the core of current comparator and the PC+DAQ type signal acquisition module is aso designed. Finally, proving trials and the real test are completed for the whole tesing system. Experimental results illustrate that the testing system meets the needs of AC characteristic test for non-linear dielectrics.