Mixed MOSFET-IGBT bridge for high-efficient Medium-Frequency Dual-Active-Bridge converter in Solid State Transformers

High power DC-DC conversion is a key element within the Solid-State-Transformer concept. In order to reduce the switching losses of the Medium-Voltage side semiconductors, a Triangular-Current-Mode modulation scheme presents an attractive option. This modulation scheme, however introduces considerable challenges in the design of the low-voltage side power electronic bridges, which need to deal with high conducted and high switched currents. In order to increase the converter´s efficiency, a combination of IGBTs and MOSFETs in a full-bridge configuration is considered. Practical hardware realizations are utilized in order to quantify the improvements introduced by the combination of these switches. Furthermore, the MOSFET´s current conduction phase is supported by parallel connected IGBTs, which are used in order to further increase the full-bridge´s efficiency, as shown by the provided experimental verification.