Multilayer Electret Based Electric Field Neutralization under Pulse Width Modulated High Voltage Waveforms

The electret based electric field neutralization approach has been reported as a novel method for mitigating partial discharge (PD) caused by defects such as triple points, airgaps, sharp edges, and bubbles. In this study, electrets are fabricated under an optimal charging condition based on the triode corona charging method. To investigate the PD mitigation performance of the fabricated electret films, a series of PD experiments are conducted on both the charged and uncharged polyvinylidene fluoride (PVDF) films under square sinusoidal pulse width modulation (SPWM) signal. Surface discharge magnitude caused by the triple points and cavity discharge magnitude caused by the presence of airgaps and bubbles with uncharged and charged PVDF are compared to determine the PD mitigation performance of electret. In addition to using single layer electrets, multiple layers of electrets are also experimented to mitigate PD caused in systems with higher voltage ratings.