Dynamic Behavior of Fillers in Liquid Dielectrics: Dielectrophoretic Orientation under Square Wave Voltage for Enhancing Charge Transport in Composites

High-voltage power modules play a critical role in energy conversion systems. However, as voltage levels increase and module miniaturization advances, severe electric field distortion at the triple point becomes increasingly problematic, leading to partial discharge and insulation failure. Nonlinear conductive fillers, when aligned in a liquid dielectric, can effectively homogenize the electric field distribution. However, due to limitations in theoretical understanding and fabrication techniques, current research remains confined to the material preparation stage, with no practical implementation in power modules. To address this gap, this study proposes a four-stage model describing the motion of fillers under a positive square wave electric field, encompassing rotation, attraction, thickening, and migration. Furthermore, the influence of filler alignment on the nonlinear electrical conductivity of the composite was systematically investigated. Finally, the composite was applied as a coating to optimize the local electric field distribution in power modules, resulting in a 34% increase in partial discharge inception voltage (PDIV) and significantly enhancing the insulation performance. This work provides an innovative approach for improving the dielectric performance of power modules, paving the way for advanced high-voltage energy conversion systems.