Switching Losses in a SiC-Based DC-DC Multilevel Boost Converter

Abstract

In the aerospace industry where the weight and power density are important design parameters, high frequency operation results in smaller passive components. Furthermore, to achieve a large voltage conversion ratio, which is a goal for payload systems, the use of transformers increases the size and power losses of the system. To fulfill the space and weight requirements, a transformer-less SiC-based DC-DC multilevel converter providing high voltage conversion ratios without an extremely high duty cycle has been realized. The experimental high switching frequency and low current results for a conventional, 3-level and 4-level converter utilizing Si and SiC based COTS diodes are presented. SiC-based multilevel converters show a higher efficiency due to the low reverse recovery and fast switching of the diodes, which results in a higher voltage conversion ratio. This translates to a lower duty cycle to obtain the required output voltage, whilst eliminating the need for complex filtering even under light load conditions.