Dielectric and partial discharge investigations on high power insulated gate bipolar transistor modules

This paper investigates on dielectric condition assessment of high power Insulated Gate Bipolar Transistor (IGBT) modules through modern dielectric and diagnostic test methods. Two groups of IGBT samples (new and aged) are selected for this purpose. The new IGBT samples are grouped as ´set-1/virgin´ and marked as ´A´, ´B´, ´C´, ´D´ and ´E´ respectively. Amongst all, a fault (electric puncture) is introduced into the sample ´E´. The samples ´A´ and ´B´ are maintained virgin while samples ´C´, ´D´ and ´E´ are subjected to partial discharge measurements as recommended by IEC60270. The samples are qualitatively ranked based on their PD level. Subsequently, the dielectric condition of each sample is measured and analyzed over a wide span and frequency. Following this, similar experiments are carried out on IGBT samples that were aged under service and their behaviour over a wide frequency is analyzed. In conclusion, the present study might provide an opportunity in improvement of diagnostic and quality control test methods that are currently exercised on IGBT modules and power conversion devices. Also, these findings enable discrimination of electrical discharges caused by IGBT modules in power conversion equipments which might help in accurate determination of their dielectric condition and reliability.