Advanced Model Predictive Control Methods for Bidirectional Three-Phase Two-Level Converter for Solid State Transformers

Solid state transformers involve three stages with the third stage being the three-phase two-level DC-AC converter. This paper investigates two different model predictive control-based methods of controlling this converter. The first one aims to reduce the average switching frequency to reduce switching losses. The second one is modulated model predictive control which can give fixed switching frequency. Both the proposed methods can realize bidirectional power flow. These two methods are compared using simulation studies in terms of active power delivered, average switching frequency, current THD and harmonic spectrum and the better one is then selected for solid state transformers application.