Model Predictive Control on Back-to-Back Parallel-Series Cascaded H-Bridge Converters

Abstract

The growth in the energy demand, caused by the continuous increase of the industrial plants capacity, has been demanding higher voltage levels of the static converters applied to the industrial equipment drives, such as motors, rolling mills, pumps, fans and compressors. This increase ends up reaching the physical limit of the power semiconductor, making it impossible to drive equipment with conventional converters connected directly to the medium voltage. Due to this technological deficit, one of the proposals in the literature is the usage of the Cascaded H-Bridge Multilevel Converter (CHB). However, the CHB topology has an operational limitation when using the Back-to-Back (B2B) configuration, since some switching states result in short circuits between the multiple isolated capacitors. The main objective of this article is to propose a high-frequency switching strategy based on the concepts of model predictive control capable of eliminating the capacitor short-circuit stages without losing the controllability and quality of current waveforms and converter voltage.