Influencing Factors of Molecular Vibration at Pulse Edge

Wide bandgap semiconductor device will withstand the square wave pulse voltage with high amplitude and high rate of change, which brings great challenges to the insulation. Because of its excellent performance, silicone elastomer is widely used in encapsulation insulation of power electronic devices. So it is necessary to study its failure mechanism under pulsed electric field. The rising and falling edges of the pulsed electric field will excite the charged molecules to vibrate. The influencing factors and internal mechanism of molecular vibration are discussed. The experimental results show that, the molecular vibration intensity decreases sharply with the increase of the pulse edge time, and increases linearly with the increase of the slope at the pulse edge. In addition, the molecular vibration intensity is also proportional to the square of the amplitude of the pulse electric field, and increases with the increase of the space charge density in the sample. Molecular vibration is an important factor leading to insulation failure, so measures need to be taken to suppress this phenomenon.