The insulation performance of high voltage and high power insulated gate bipolar transistor (IGBT) devices is restricted by the insulation performance of silicone gel

which is the device packaging material of IGBT devices. At present

there are few researches on the inception characteristics and influence factors of partial discharge in silicone gel under the device application condition

namely the positive polarity repetitive square wave. In this paper

an experimental platform of partial discharge in silicone gel under positive polarity repetitive square wave voltage was established

the partial discharge inception characteristics in silicone gel under positive polarity repetitive square wave voltage were obtained by photoelectric combined detection method and the mechanism was analyzed

the effects of positive polarity repetitive square wave parameters including rise time

fall time

duty cycle and frequency on partial discharge incept

ion voltage (

PDIV

) and instantaneous discharge voltage in silicone gel were preliminarily mastered. The results show that

PDIV

has little change with the rise time

but it decreases by 10.4% at 200 ms compared with 150 ms. When the fall time is higher than 100 ms

PDIV

presents an approximately linear rising trend

and remains relatively stable when the duty cycle is between 30% and 70%. As the frequency increases

PDIV

has a minimum value at 100 Hz. The research results of this paper have certain guiding significance for the cognition of insulation characteristics of silicone gel used in IGBT device internal packaging under device application conditions.