Mitigating Partial Discharge in PWM Voltage Systems Using Electrets

Advancing power semiconductor technology offers high efficiency and enables both high gravimetric and volumetric power densities. However, the locally enhanced electric field in the power-dense designs and recurring, steep pulse width modulated (PWM) voltage stress caused by PEC promote partial discharge (PD), a chronic dielectric issue that accelerate dielectric aging and device failure. Unlike conventional electric field grading approaches, the proposed electret-based PD mitigation approach neutralizes electric field to prevent PDs generated at triple points, sharp edges, and cavities. In this study, the electret-based PD mitigation approach is carried out in a PWM driven system. PD experiments were conducted with uncharged polyvinylidene fluoride (PVDF) and charged PVDF (electret) for various duty cycles while the PD magnitudes and PD repetition rates were recorded. The measured PD data are compared to evaluate the PD-mitigating performance of electrets.