脉冲电压下聚酰亚胺空间电荷行为及其机理研究

Space Charge Behavior and Mechanism of Polyimide Under Pulse Voltage

电力电子装备长期处于高重复频率、陡上升时间脉冲电压运行工况,绝缘更容易发生劣化和早期失效。为探究脉冲电压下绝缘失效的微观机理,对ns级别下的脉冲边沿前后空间电荷分布情况进行研究对比,探究了电场强度、硅油对脉冲边沿时刻电荷振动波形的影响。通过分析不同脉冲上升时间下的电荷振动波形及电压波形频谱、电荷积聚特性,阐明了脉冲电压边沿时刻电荷振动机理以及ns脉冲下电荷行为对绝缘劣化影响机理。研究发现,ns脉冲上升沿和下降沿前后电荷分布特性存在差异,在脉冲边沿处发现了特殊的空间电荷迁移行为;电场强度会影响异极性电荷的积累速度及积累量,从而影响电荷振动波形的形状;电极与试样之间涂敷硅油会影响电荷振动波形的极性;5×10^(6)~1×10^(7)Hz频段的电压分量对空间电荷振动起主要作用;ns脉冲电压下电荷积聚导致电场畸变更加严重。

The insulation of power electronic equipment is more likely to deteriorate and fail early because it is operated with high repetition rate and steep rise time pulse voltage for a long time.In order to explore the microscopic mechanism of insulation failure under pulse voltage,the space charge distribution before and after the pulse edge at the nanosecond level was studied and compared,and the influences of electric field strength and silicone oil on the charge vibration waveform at the pulse edge were explored.Based on an analysis of the spectrum of charge vibration waveform and voltage waveform and the charge accumulation characteristics at different pulse rise times,the charge vibration mechanism at the time of pulse voltage edge and the influence mechanism of charge behavior on insulation degradation under nanosecond pulse were expounded.It was found that the charge distribution characteristics before and after the rising edge and falling edge of the nanosecond pulse were different,and a special space charge migration behavior was found at the pulse edge;the electric field strength would affect the accumulation speed and amount of the heteropolar charge,thereby affecting the shape of charge vibration waveform;the application of silicone oil between the electrode and the sample would affect the polarity of the charge vibration waveform;the voltage component in the 5×106~1×107 Hz frequency band played a major role in the space charge vibration;the charge accumulation under the nanosecond pulse voltage caused serious electric field distortion.