Optically Isolated Rogowski Coil: Non-Invasive Current Measurement With High d <i>v</i> /d <i>t</i> Immunity for WBG Device

Rogowski coil (RC) has been extensively employed for current measurement of power devices owning to its non- invasiveness, flexibility and accuracy. However, the increasing blocking voltage and accelerated switching speed of wide-bandgap (WBG) devices impose significant challenges on RC-based measurement systems, primarily manifested as more severe electric field interference. In this letter, a novel optically isolated Rogowski coil (Opt-RC) is proposed to address the electric field interference issues. By incorporating optical isolation, the original common-mode (CM) interference pathways are effectively interrupted, substantially mitigating CM noise without modifying the coil structure and compromising bandwidth. Furthermore, the excellent insulating properties provided by optical fiber imparts the Opt-RC with significant potential for accurate current measurement in high-voltage scenarios. Comprehensive experiments confirm the electric field interference immunity and excellent insulation of the proposed Opt-RC.