Behavioral Modeling of Ground Current in Filter Inductors of Medium-Voltage SiC-MOSFET-Based Converters

Abstract

This paper analyzes the phenomenon of ground current in the filter inductors (with a grounded core/frame) of medium-voltage (MV) SiC-MOSFET-based. The inductor ground current is generated during the switching transients, due to the capacitive coupling between the winding and the core/frame. A general three-terminal equivalent circuit is proposed for representing the capacitive couplings of the filter inductors, which allows the extraction of equivalent admittances between the terminals by using the system identification tool, and thus the ground current can be accurately simulated in the frequency range of concern (up to 100 MHz in this paper). The simulated ground current based on the behavioral model match closely with the experimental results measured in a medium voltage SiC MOSFET based double-pulse test.