Analysis of Multilevel High Bandwidth Converters Based on SiC Technology for Automotive and Aircraft Applications

This paper aims to explore the influence of converter topology and output filter on its bandwidth, with focus on the loss mechanisms of SiC (Silicon Carbide) MOSFETs and the nonidealities of switching cells. A model is presented to assess the harmonic content of output current as a function of the number of interleaved switching cells and the topology of the output filter with the intention to estimate the converter bandwidth. Furthermore, loss mechanisms of SiC MOSFETs are reviewed in order to find the relationship between the maximum switching frequency of each switching cell and the desired converter output current. Precise modeling of THD is presented to evaluate the impact of the inductor parasitic capacitance on output current THD. High dv/dt rate in high bandwidth converters can significantly increase the harmonic high frequency content in the output current of each switching cell. Results indicate that the use of multilevel converters represents a promising approach for high bandwidth converters. However, the design of output inductors must be carefully considered, as these components have significant impact on the THD of the output current due to the influence of parasitic capacitances and non-linearities of the magnetic material.