2-Level Si IGBT Converter with Parallel Part-Rated SiC Converter Providing Partial Power Transfer and Active Filtering

This paper investigates the potential of utilising partially rated Silicon Carbide (SiC) MOSFET based converters as active filters for slower switching silicon IGBT based converters in multi-megawatt applications. This allows the effective switching frequency of the overall converter to be significantly increased, reducing the requirement for external filters and increasing the converters current control bandwidth, without relying on a wholly SiC MOSFET based approach. If a parallel DC bus arrangement is adopted this also opens up the potential for partial-load efficiency improvements. A finite step model predictive current controller is adopted, which allows significant flexibility in how the converter is operated.